pregnancy

Pregnancy

Definition

The period from conception to birth. After the egg is fertilized by a sperm and then implanted in the lining of the uterus, it develops into the placenta and embryo, and later into a fetus. Pregnancy usually lasts 40 weeks, beginning from the first day of the woman's last menstrual period, and is divided into three trimesters, each lasting three months.

Description

Pregnancy is a state in which a woman carries a fertilized egg inside her body. Due to technological advances, pregnancy is increasingly occurring among older women in the United States.

First month

At the end of the first month, the embryo is about a third of an inch long, and its head and trunk-plus the beginnings of arms and legs-have started to develop. The embryo receives nutrients and eliminates waste through the umbilical cord and placenta. By the end of the first month, the liver and digestive system begin to develop, and the heart starts to beat.

Second month

In this month, the heart starts to pump and the nervous system (including the brain and spinal cord) begins to develop. The 1 in (2.5 cm) long fetus has a complete cartilage skeleton, which is replaced by bone cells by month's end. Arms, legs and all of the major organs begin to appear. Facial features begin to form.

Third month

By now, the fetus has grown to 4 in (10 cm) and weighs a little more than an ounce (28 g). Now the major blood vessels and the roof of the mouth are almost completed, as the face starts to take on a more recognizably human appearance. Fingers and toes appear. All the major organs are now beginning to form; the kidneys are now functional and the four chambers of the heart are complete.

Fourth month

The fetus begins to kick and swallow, although most women still can't feel the baby move at this point. Now 4 oz (112 g), the fetus can hear and urinate, and has established sleep-wake cycles. All organs are now fully formed, although they will continue to grow for the next five months. The fetus has skin, eyebrows, and hair.

Fifth month

Now weighing up to a 1 lb (454 g) and measuring 8-12 in (20-30 cm), the fetus experiences rapid growth as its internal organs continue to grow. At this point, the mother may feel her baby move, and she can hear the heartbeat with a stethoscope.

Sixth month

Even though its lungs are not fully developed, a fetus born during this month can survive with intensive care. Weighing 1-1.5 lbs (454-681 g), the fetus is red, wrinkly, and covered with fine hair all over its body. The fetus will grow very fast during this month as its organs continue to develop.

Seventh month

There is a better chance that a fetus born during this month will survive. The fetus continues to grow rapidly, and may weigh as much as 3 lb (1.3 kg) by now. Now the fetus can suck its thumb and look around its watery womb with open eyes.

Eighth month

Growth continues but slows down as the baby begins to take up most of the room inside the uterus. Now weighing 4-5 lbs (1.8-2.3 kg) and measuring 16-18 in (40-45 cm) long, the fetus may at this time prepare for delivery next month by moving into the head-down position.

Ninth month

Adding 0.5 lb (227 g) a week as the due date approaches, the fetus drops lower into the mother's abdomen and prepares for the onset of labor, which may begin any time between the 37th and 42nd week of gestation. Most healthy babies will weigh 6-9 lb (2.7-4 kg) at birth, and will be about 20 in. long.

Causes and symptoms

The first sign of pregnancy is usually a missed menstrual period, although some women bleed in the beginning. A woman's breasts swell and may become tender as the mammary glands prepare for eventual breastfeeding. Nipples begin to enlarge and the veins over the surface of the breasts become more noticeable.Nausea and vomiting are very common symptoms and are usually worse in the morning and during the first trimester of pregnancy. They are usually caused by hormonal changes, in particular, increased levels of progesterone. Women may feel worse when their stomach is empty, so it is a good idea to eat several small meals throughout the day, and to keep things like crackers on hand to eat even before getting out of bed in the morning.Many women also feel extremely tired during the early weeks. Frequent urination is common, and there

Pregnancy usually lasts 40 weeks in humans, beginning from the first day of the woman's last menstrual period, and is divided into three trimesters. The illustration above depicts the position of the developing fetus during each trimester. (Illustration by Electronic Illustrators Group.)may be a creamy white discharge from the vagina. Some women crave certain foods, and an extreme sensitivity to smell may worsen the nausea. Weight begins to increase.In the second trimester (13-28 weeks) a woman begins to look noticeably pregnant and the enlarged uterus is easy to feel. The nipples get bigger and darker, skin may darken, and some women may feel flushed and warm. Appetite may increase. By the 22nd week, most women have felt the baby move. During the second trimester, nausea and vomiting often fade away, and the pregnant woman often feels much better and more energetic. Heart rate increases as does the volume of blood in the body.By the third trimester (29-40 weeks), many women begin to experience a range of common symptoms. Stretch marks may develop on abdomen, breasts, and thighs, and a dark line may appear from the navel to pubic hair. A thin fluid may be expressed from the nipples. Many women feel hot, sweat easily and often find it hard to get comfortable. Kicks from an active baby may cause sharp pains, and lower backaches are common. More rest is needed as the woman copes with the added stress of extra weight. Braxton Hicks contractions may get stronger.At about the 36th week in a first pregnancy (later in repeat pregnancies), the baby's head drops down low into the pelvis. This may relieve pressure on the upper abdomen and the lungs, allowing a woman to breathe more easily. However, the new position places more pressure on the bladder.A healthy gain for most women is between 25 and 35 pounds. Women who are overweight should gain less; and women who are underweight should gain more. On average, pregnant women need an additional 300 calories a day. Generally, women will gain three to five pounds in the first three months, adding one to two pounds a week until the baby is born. An average, healthy full-term baby at birth weighs 7.5 lb (3.4 kg), and the placenta and fluid together weigh another 3.5 lb. The remaining weight that a woman gains during pregnancy is mostly due to water retention and fat stores. Her breasts, for instance, gain about 2 lb. in weight, and she gains another 4 lb due to the increased blood volume of pregnancy.In addition to the typical, common symptoms of pregnancy, some women experience other problems that may be annoying, but which usually disappear after delivery. Constipation may develop as a result of food passing more slowly through the intestine. Hemorrhoids and heartburn are fairly common during late pregnancy. Gums may become more sensitive and bleed more easily; eyes may dry out, making contact lenses feel painful. Pica (a craving to eat substances other than food) may occur. Swollen ankles and varicose veins may be a problem in the second half of pregnancy, and chloasma may appear on the face.Chloasma, also known as the "mask of pregnancy" or melasma, is caused by hormonal changes that result in blotches of pale brown skin appearing on the forehead, cheeks, and nose. These blotches may merge into one dark mask. It usually fades gradually after pregnancy, but it may become permanent or recur with subsequent pregnancies. Some women also find that the line running from the top to the bottom of their abdomen darkens. This is called the linea nigra.While the above symptoms are all considered to be normal, there are some symptoms that could be a sign of a more dangerous underlying problem. A pregnant woman with any of the following signs should contact her doctor immediately:

abdominal pain
rupture of the amniotic sac or leaking of fluid from the vagina
bleeding from the vagina
no fetal movement for 24 hours (after the fifth month)
continuous headaches
marked, sudden swelling of eyelids, hands, or face during the last three months
dim or blurry vision during last three months
persistent vomiting

Diagnosis

Many women first discover they are pregnant after a positive home pregnancy test. Pregnancy urine tests check for the presence of human chorionic gonadotropin (hCG), which is produced by a placenta. The newest home tests can detect pregnancy on the day of the missed menstrual period.Home pregnancy tests are more than 97% accurate if the result is positive, and about 80% accurate if the result is negative. If the result is negative and there is no menstrual period within another week, the pregnancy test should be repeated. While home pregnancy tests are very accurate, they are less accurate than a pregnancy test conducted at a lab. For this reason, women may want to consider having a second pregnancy test conducted at their doctor's office to be sure of the accuracy of the result.Blood tests to determine pregnancy are usually used only when a very early diagnosis of pregnancy is needed. This more expensive test, which also looks for hCG, can produce a result within nine to 12 days after conception.Once pregnancy has been confirmed, there are a range of screening tests that can be done to screen for birth defects, which affect about 3% of unborn children. Two tests are recommended for all pregnant women: alpha-fetoprotein (AFP) and the triple marker test.Other tests are recommended for women at higher risk for having a child with a birth defect. This would include women over age 35, who had another child or a close relative with a birth defect, or who have been exposed to certain drugs or high levels of radiation. Women with any of these risk factors may want to consider amniocentesis, chorionic villus sampling (CVS) or ultrasound.

Other prenatal tests

There are a range of other prenatal tests that are routinely performed, including:

PAP test
gestational diabetes screening test at 24-28 weeks
tests for sexually transmitted diseases
urinalysis
blood tests for anemia or blood type
screening for immunity to various diseases, such as German measles

Treatment

Prenatal care is vitally important for the health of the unborn baby. A pregnant woman should be sure to eat a balanced, nutritious diet of frequent, small meals. Women should begin taking 400 mcg of folic acid several months before becoming pregnant, as folic acid has been shown to reduce the risk of spinal cord defects, such as spina bifida.No medication (not even a nonprescription drug) should be taken except under medical supervision, since it could pass from the mother through the placenta to the developing baby. Some drugs, called teratogens, have been proven harmful to a fetus, but no drug should be considered completely safe (especially during early pregnancy). Drugs taken during the first three months of a pregnancy may interfere with the normal formation of the baby's organs, leading to birth defects. Drugs taken later on in pregnancy may slow the baby's growth rate, or they may damage specific fetal tissue (such as the developing teeth), or cause preterm birth.To have the best chance of having a healthy baby, a pregnant woman should avoid:

smoking
alcohol
street drugs
large amounts of caffeine
artificial sweeteners

Nutrition

Women should begin following a healthy diet even before they become pregnant. This means cutting back on high-calorie, high-fat, high-sugar snacks, and increasing the amount of fruits, vegetables and whole grains in her diet. Once she becomes pregnant, she should make sure to get at least six to 11 servings of breads and other whole grains, three to five servings of vegetables, two to four servings of fruits, four to six servings of milk and milk products, three to four servings of meat and protein foods, and six to eight glasses of water. She should limit caffeine to no more than one soft drink or cup of coffee per day.

Prognosis

Pregnancy is a natural condition that usually causes little discomfort provided the woman takes care of herself and gets adequate prenatal care. Childbirth education classes for the woman and her partner help prepare the couple for labor and delivery.

Key terms

Alpha-fetoprotein — A substance produced by a fetus' liver that can be found in the amniotic fluid and in the mother's blood. Abnormally high levels of this substance suggests there may be defects in the fetal neural tube, a structure that will include the brain and spinal cord when completely developed. Abnormally low levels suggest the possibility of Down' syndrome.Braxton Hicks' contractions — Short, fairly painless uterine contractions during pregnancy that may be mistaken for labor pains. They allow the uterus to grow and help circulate blood through the uterine blood vessels.Chloasma — A skin discoloration common during pregnancy, also known as the "mask of pregnancy" or melasma, in which blotches of pale brown skin appear on the face. It is usually caused by hormonal changes. The blotches may appear in the forehead, cheeks, and nose, and may merge into one dark mask. It usually fades gradually after pregnancy, but it may become permanent or recur with subsequent pregnancies. Some women may also find that the line running from the top to the bottom of their abdomen darkens. This is called the linea nigra.Embryo — An unborn child during the first eight weeks of development following conception (fertilization with sperm). For the rest of pregnancy, the embryo is known as a fetus.Fetus — An unborn child from the end of the eights week after fertilization until birth.Human chorionic gonadotropin (hCG) — A hormone produced by the placenta during pregnancy.Placenta — The organ that develops in the uterus during pregnancy that links the blood supplies of the mother and baby.Rhythm method — The oldest method of contraception with a very high failure rate, in which partners periodically refrain from having sex during ovulation. Ovulation is predicted on the basis of a woman's previous menstrual cycle.Spina bifida — A congenital defect in which part of the vertebrae fail to develop completely, leaving a portion of the spinal cord exposed.

Prevention

There are many ways to avoid pregnancy. A woman has a choice of many methods of contraception which will prevent pregnancy, including (in order of least to most effective):

spermicide alone
natural (rhythm) method
diaphragm or cap alone
condom alone

diaphragm with spermicide
condom with spermicide
intrauterine device (IUD)
contraceptive pill
sterilization (either a man or woman)
avoiding intercourse

Resources

Organizations

Healthy Mothers, Healthy Babies National Coalition. 409 12th St., Washington, DC 20024. (202) 638-5577.National Institute of Child Health and Human Development. 9000 Rockville Pike, Bldg. 31, Rm. 2A32, Bethesda, MD 20892. (301) 496-5133.Positive Pregnancy and Parenting Fitness. 51 Saltrock Rd., Baltic, CT 06330. (203) 822-8573.

Other

Doulas of North America http://www.dona.com.Planned Parenthood. http://www.plannedparenthood.org.Pregnancy Information. http://www.childbirth.org.

pregnancy

[preg´nan-se] the condition of having a developing embryo or fetus in the body, after union of an oocyte (ovum) and spermatozoon" >spermatozoon. The average gestation period" >gestation period for a human pregnancy is 10 lunar months (280 days) from the first day of the last menstrual period.Conception. Once a month an ovum (secondary oocyte) matures in one of the ovaries" >ovaries and travels down the nearby fallopian tube" >fallopian tube to the uterus" >uterus; this process is called ovulation" >ovulation. Fertilization" >At Fertilization, which must take place within a day or two of ovulation, one of the spermatozoa unites with the ovum to form a zygote. The zygote then implants itself in the wall of the uterus, which is richly supplied with blood, and begins to grow. (See also reproduction.)Signs of Pregnancy. Usually the first indication of pregnancy is a missed menstrual period. Unless the period is more than 10 days late, however, this is not a definite indication, since many factors, including a strong fear of pregnancy, can delay menstruation. Nausea, or morning sickness, usually begins in the fifth or sixth week of pregnancy. About 4 weeks after conception, changes in the breasts become noticeable: there may be a tingling sensation in the breasts, the nipples enlarge, and the areolae (dark areas around nipples) may become darker. Frequent urination, another early sign, is the result of expansion of the uterus, which presses on the bladder.
Other signs of pregnancy include softening of the cervix and filling of the cervical canal with a plug of mucus. Early in labor this plug is expelled and there is slight bleeding; expulsion of the mucous plug is known as show" >show and indicates the beginning of cervical dilatation. chadwick's sign" >chadwick's sign of pregnancy refers to a bluish color of the vagina which is a result of increased blood supply to the area.
When the abdominal wall becomes stretched there may be a breaking down of elastic tissues, resulting in depressed areas in the skin which are smooth and reddened. These markings are called striae gravidarum" >striae gravidarum. In subsequent pregnancies the old striae appear as whitish streaks and frequently do not disappear completely.
There are several fairly accurate laboratory tests for pregnancy; all are designed to detect human gonadotropin" >chorionic gonadotropin (hCG), a hormone produced by living chorionic placental tissue and evident in the blood and urine of pregnant women. See also pregnancy tests.Growth of the Fetus. The average pregnancy lasts about 280 days, or 40 weeks, from the date of conception to childbirth. Since the exact date of conception usually is not known, the estimated date of delivery can be calculated using nägele's rule. This is approximate, since pregnancy may be shorter than the average or can last as long as 300 days. (For stages of growth of the fetus, see fetus.)Care of the Fetus. A host of influences can adversely affect the growth and development of the fetus and his or her chances for survival and good health after birth. The diet of the mother should be nutritious and well-balanced so that the fetus receives the necessary food elements for development and maturity of body structures. It is especially important that the mother receive adequate protein in her diet, because a protein deficiency can hamper fetal intellectual development. Supplemental iron and vitamins usually are recommended during pregnancy.
There is now less emphasis on severe restriction of the mother's dietary intake to maintain a limited weight gain. The average gain is about 28 lb during pregnancy, and either starvation diets or forced feedings can be unhealthy for the mother and hazardous for the fetus. Ideally, the mother should achieve normal weight before she becomes pregnant because obesity increases the possibility of eclampsia and other serious complications of pregnancy. Mothers who are underweight are more likely to deliver immature babies who, by virtue of their physiologic immaturity, are more likely to suffer from birth defects, hyaline membrane disease, and other developmental disorders of the newborn.
Other factors affecting the fetus include certain drugs taken by the mother during pregnancy. A well-known example is thalidomide, which inhibits the growth of the extremities of the fetus, resulting in gross deformities. Many drugs, including prescription as well as nonprescription medications, are now believed to be capable of causing fetal abnormalities. In addition, consumption of alcohol during pregnancy may result in fetal alcohol syndrome. Most health care providers recommend that all drugs be avoided during pregnancy except those essential to the control of disease in the mother.
Diseases that increase the risk of obstetrical complications include diabetes, heart disease, hypertension, kidney disease, and anemia. rubella" >rubella (German measles) can be responsible for many types of birth defects, particularly if the mother contracts it in the first 3 months of pregnancy. Sexually transmitted diseases can have tragic effects on the baby, even though the symptoms in the mother are minor at the time of pregnancy. syphilis is particularly dangerous because it is one of the few diseases that can be transmitted to the fetus in utero. The baby is either stillborn or born infected, and rarely escapes physical or mental defects or both. Successful treatment of the mother before the fifth month of pregnancy will prevent infection in the infant.
During the birth process the infant may be infected with gonorrhea as it passes through the birth canal. Gonorrheal infection of the eyes can cause blindness. herpes simplex Type II involving the genitals of the mother can also be transmitted to the infant at birth. The mortality and morbidity rates for such infected infants are high.
The age of the mother is also an important factor in the well-being of the fetus. The mortality and morbidity rate for infants born of mothers below age 15 and above 40 are higher than for those of mothers between these ages.
Recently developed tests to monitor fetal health have taken much of the guesswork out of predicting the chances of survival and health status of the fetus after birth. Such tests and evaluation techniques include amniocentesis, chemical and hormonal assays, biophysical profiles, testing for alpha-fetoprotein, ultrasound examinations, electronic surveillance of fetal vital signs and reaction to uterine contractions, and analyses of the infant's blood during labor.Prenatal Care. The care of the mother during her entire pregnancy is important to her well-being and that of the fetus she is carrying. It will help provide ease and safety during pregnancy and childbirth. The health care provider learns about the patient's physical condition and medical history, and can detect possible complications before they become serious.
On the first prenatal visit the patient's medical history is taken in considerable detail, including any diseases or operations she has had, the course of previous pregnancies, if any, and whether there is a family history of multiple births or of diabetes mellitus or other chronic diseases. The first visit also includes a thorough physical examination and measurement of the pelvis. Blood samples are taken for screening for rubella and sexually transmitted diseases such as syphilis, hepatitis B, chlamydiosis, infection by the human immunodeficiency virus, and other conditions. A complete blood count is also needed. Urine is tested for albumin and sugar and examined microscopically. On subsequent visits the patient brings a urine specimen, collected upon arising that morning, to be tested for albumin and glucose. At each prenatal visit her blood pressure is taken and recorded and she is weighed. In the second trimester, when the uterus becomes an abdominal organ, the height of the fundus is measured at each visit. After the sixth month a rule such as mcdonald's rule can be applied to assess fetal growth.
Patients who are considered high-risk mothers usually are sent to a specialist and the infant is delivered at a regional hospital where sophisticated monitoring equipment and laboratory tests are available, and specially trained personnel can attend to the needs of the mother and her infant.Discomforts and Complications.morning sickness usually appears in the early months of pregnancy and rarely lasts beyond the third month. Often it requires no treatment or can be relieved by such simple measures as eating dry crackers and tea before rising. Indigestion and heartburn are best prevented by avoiding foods that are difficult to digest, such as cucumbers, cabbage, cauliflower, spinach, onions, and rich foods. Constipation usually can be corrected by diet or a mild laxative; strong laxatives should not be used unless prescribed by the health care provider.
A visit to a dentist early in pregnancy is a good idea to forestall any possibility of infection arising from tooth decay. Pregnancy does not encourage tooth decay. Hemorrhoids sometimes occur in pregnancy because of pressure from the enlarged uterus on the veins in the rectum. The health care provider should be consulted for treatment. varicose veins also result from pressure of the uterus, which restricts the flow of blood from the legs and feet. Lying flat with the feet raised on a pillow several times a day will help relieve swelling and pain in the legs. In more difficult cases the health care provider may prescribe an elastic bandage or support stockings.
Backache during pregnancy is caused by the heavy abdomen pulling on muscles that are not normally used, and can be relieved by rest, sensible shoes, and good posture. Swelling of the feet and ankles usually is relieved by rest and by remaining off the feet for a day or two. If the swelling does not disappear, the health care provider should be informed since it may be an indication of a more serious complication.
Shortness of breath is common in the later stages of pregnancy. If at any time it becomes so extreme that the woman cannot climb a short flight of stairs without discomfort, the health care provider should be consulted. If a mild shortness of breath interferes with sleep, lying in a half-sitting position, supported by several pillows, may help.
The more serious complications of pregnancy include pyelitis, hyperemesis gravidarum, eclampsia, and placenta previa and abruptio placentae.

Uterine levels in pregnancy.abdominal pregnancy ectopic pregnancy within the peritoneal cavity.ampullar pregnancy ectopic pregnancy in the ampulla of the fallopian tube.cervical pregnancy ectopic pregnancy within the cervical canal.combined pregnancy simultaneous intrauterine and extrauterine pregnancies.cornual pregnancy pregnancy in a horn of the uterus.ectopic pregnancy pregnancy in which the fertilized ovum becomes implanted outside the uterus instead of in the wall of the uterus; this is almost always in a fallopian tube (tubal pregnancy), although occasionally the ovum develops in the abdominal cavity, ovary, or cervix uteri. Called also extrauterine pregnancy.
In a tubal pregnancy a spontaneous abortion may occur, but more often the fetus will grow to a size large enough to rupture the tube. This is an emergency situation requiring immediate treatment. The symptoms of such a tubal rupture are vaginal bleeding and severe pain in one side of the abdomen. Prompt surgery is necessary to remove the damaged tube and the fetus, and to stop the bleeding. Fortunately, the removal of one tube usually leaves the other one intact, so that future pregnancy is possible. Patients who are Rh-negative should be given Rh₀ (D) immune globulin (RhoGAM) after ectopic pregnancy for isoimmunization protection in future pregnancies.

Ectopic pregnancy. The fallopian tube is the most common site for ectopic pregnancies but they can also occur on the ovary or the peritoneal surface of the abdominal cavity. From Damjanov, 2000.extrauterine pregnancy ectopic pregnancy.false pregnancy development of all the signs of pregnancy without the presence of an embryo; called also pseudocyesis and pseudopregnancy.interstitial pregnancy pregnancy in that part of the fallopian tube within the wall of the uterus.intraligamentary pregnancy (intraligamentous pregnancy) ectopic pregnancy within the broad ligament.molar pregnancy conversion of the fertilized ovum into a mole.multiple pregnancy the presence of more than one fetus in the uterus at the same time.mural pregnancy interstitial pregnancy.ovarian pregnancy pregnancy occurring in an ovary.phantom pregnancy false pregnancy due to psychogenic factors.surrogate pregnancy one in which a woman other than the female partner is artificially impregnated with the male partner's sperm. The resultant child represents only the male of the marital unit, and may be adopted by the female.pregnancy tests procedures for early determination of pregnancy. By the first missed menstrual period or shortly thereafter, human chorionic gonadotropin (hCG), a hormone secreted by the placenta, is present in the blood and urine of a pregnant woman. It was formerly determined by bioassay in which a urine or serum specimen was injected into a laboratory animal and the response of ovarian tissue was noted. All testing now uses immunologic techniques based on antigen-antibody binding between hCG and anti-hCG antibody. There are several commercial kits available (see early pregnancy tests), based on the agglutination of hCG-coated latex particles by anti-hCG serum, which is inhibited if the urine specimen added to the serum contains hCG. Clinical laboratories generally use radioimmunoassay or radioreceptor assay to determine serum hCG levels. These methods are more accurate and less likely to produce false-positive results.tubal pregnancy the most common type of pregnancy" >ectopic pregnancy, occurring within a fallopian tube" >fallopian tube.tuboabdominal pregnancy ectopic pregnancy occurring partly in the fimbriated end of the fallopian tube and partly in the abdominal cavity.tubo-ovarian pregnancy pregnancy at the fimbriae of the fallopian tube.

preg·nan·cy

maieusiophobia.

preg·nan·cy

(preg'năn-sē), The state of a female after conception and until the termination of the gestation. Synonym(s): fetation, gestation, gravidism, graviditas [L. praegnans (praegnant-), pregnant, fr. prae, before, + gnascor, pp. natus, to be born]

pregnancy

(prĕg′nən-sē)n. pl. pregnan·cies a. The condition of being pregnant: a test for pregnancy.b. An instance of being pregnant: Her second pregnancy was easy.c. The period during which one is pregnant: the first trimester of pregnancy.

pregnancy

Obstetrics The state of gestation; the period of time from confirmation of implantation of a fertilized egg within the uterus–presumptive signs of pregnancy include missed menses or a positive pregnancy test [45 CFR 46.203(b)]–until the fetus has entirely left the uterus–ie, been delivered. See At-risk pregnancy, Cervical pregnancy, Clinical pregnancy, Crisis pregnancy, Ectopic pregnancy, Fatty liver of pregnancy, High-risk pregnancy, Mole pregnancy, Multifetal pregnancy, Postterm pregnancy, Pseudopreganancy, PUPPP, Selective termination of pregnancy, Sympathy pregnancy, Teenage pregnancy, Tubal pregnancy, Unwanted pregnancy.

preg·nan·cy

(preg'năn-sē) The state of a female after conception and until the termination of the gestation.
Synonym(s): gestation. [L. praegnans (praegnant-), pregnant, fr. prae, before, + gnascor, pp. natus, to be born]

pregnancy

(preg'nan-se) [L. praegnans, with child, pregnant] The condition of having a developing embryo or fetus in the body after successful conception. The average duration of pregnancy is about 280 days. Estimation of the date on which delivery should occur is based on the first day of the last menstrual period.Naegeli rule; table; prenatal care; prenatal diagnosis;

Demographics

About 7 million American women become pregnant each year, and about two thirds of these pregnancies result in live births. In 2009, there were 4,143,000 live births in the U.S.

Signs and Symptoms

Presumptive and probable signs are those commonly associated with pregnancy but may be due to other causes, such as oral contraceptive therapy. Presumptive symptoms include amenorrhea, nausea and vomiting, breast tenderness, urinary frequency, fatigue, chloasma, vaginal hyperemia (Chadwick sign), and “quickening.” Probable signs include increased abdominal girth, palpable fetal outline, softening of the lower uterine segment (Hegar sign), softening of the cervix (Goodell sign), and immunodiagnostic pregnancy tests. Positive signs and symptoms of pregnancy are auscultation of fetal heart sounds, fetal movements felt by the examiner, and an identifiable embryonic outline on ultrasound.

Physical Changes

The pregnant woman experiences many physiological alterations related to the increased levels of estrogen and progesterone and to the demands of the growing fetus; every system in the woman's body responds to these changes.

Reproductive tract changes: Alterations in uterine size, shape, and consistency include an increase in uterine muscle mass over the months of pregnancy. In response to elevated estrogen and progesterone levels, the cervix and lower uterine segment soften. A thick mucous plug fills the cervical canal. Vaginal secretions increase, and vaginal pH is more acidic (pH = 3.5 to 6.0). Change in vaginal pH discourages the survival and multiplication of bacteria; however, it also encourages infection by Candida albicans. The vagina elongates as the uterus rises in the pelvis; the mucosa thickens, with increases in secretions, vascularity, and elasticity. See: Chadwick sign; Goodell sign; Hegar sign

Breast changes: The breasts become enlarged, tender, and more nodular. The areolae darken; the nipples become more sensitive and erectile; and Montgomery's tubercles enlarge. Colostrum may leak out during the last trimester, as the breasts prepare for lactation.

Endocrine glands: The size and activity of the thyroid gland increase markedly. Thyroid-binding globulin and triiodothyronine levels rise, while thyroid-stimulating hormone levels drop slightly. These changes allow the pregnant woman to meet the endocrine needs imposed by the developing fetus, and other body changes that occur during pregnancy. Pituitary activity increases; prolactin levels increase ensuring lactation; placental hormones prevent ovulation and encourage development of the corpus luteum. Parathyroid activity decreases during the first trimester, then increases throughout the pregnancy to meet the increasing calcium demands of the fetus. Insulin resistance increases; this poses a risk, for some women, of glucose intolerance or gestational diabetes mellitus.

Cardiovascular alterations: Circulating blood volume increases progressively throughout pregnancy, peaking in the middle of the third trimester. Although the red blood cell count rises by about 30%, a 50% increase in blood volume creates dilutional anemia. The lower relative hematocrit decreases the viscosity of the blood . However, a hemoglobin concentration of less than 11 g is usually due to iron deficiency. Rising levels of clotting factors VII, VIII, IX, X, fibrinogen, and von Willebrand factor increase coagulability. The pulse rate increases, along with cardiac stroke volume. Peripheral vascular resistance drops. Mid-trimester blood pressure may be slightly lower than normal but remains essentially unchanged.

Skeletal system: Softening and increased mobility of the pelvic articulations is reflected in the waddling gait of pregnancy. As pregnancy progresses, the woman's center of gravity shifts, and the lumbar curve increases to compensate for the growing anterior weight of the gravid uterus. Problems with dental caries may become more prominent during pregnancy but can be prevented with oral rinses (such as chlorhexidine) and regular brushing and flossing.

Respiratory system: The effects of progesterone on smooth muscle include a decreased airway resistance, which enables the woman to meet her increased needs for oxygen by permitting a 30% to 40% increase in tidal volume and a 15% to 20% rise in oxygen consumption. The effects of estrogen include edema and congestion of the nasal mucosa, reflected in nosebleeds and nasal stuffiness.

Gastrointestinal system: Nausea and vomiting is the single most common complaint during the first trimester. Progesterone-related diminished motility contributes to common complaints of heartburn and constipation. Hemorrhoids are common and caused by increased pressure in the lower pelvis and constipation.

Immune system Alterations in T helper cell dominance produce immunological tolerance for the fetus and the placenta, both of which contain antigens that are alien to the mother. During pregnancy, autoimmune diseases such as rheumatoid arthritis or systemic lupus erythematosus tend to become less active.

Skin: Pigmentation changes in pregnancy include chloasma (the so-called mask of pregnancy), areolar darkening, and linea nigra (a pigmented line that vertically bisects the abdomen). They reflect estrogen-related stimulation of skin melanocytes. Striae gravidarum, also called stretch marks, may appear in the skin of the abdomen, breasts, and thighs.

Urinary system: By middle of the first trimester, the glomerular filtration rate has risen by about 50%; in compensation, tubular reabsorption also increases. Although urinary frequency is common in the first and last trimesters, bladder capacity actually increases; however, pressure from the growing uterus reduces the volume required to stimulate voiding. During the second trimester, the uterus rises out of the pelvis, becoming an abdominal organ and relieving bladder compression until late in the third trimester.

Weight: In average-sized individuals, expected first trimester weight gain is 2 to 5 lb. Total weight gain and the pattern by which it increases should be monitored to enable early signs of pregnancy-related problems common to the particular point in gestation. The Institute of Medicine recommends the following weight gains during singleton pregnancies: a woman with a prepregnancy body mass index less than 19.8 should gain 25 to 39 lb (11.4 to 17.7 kg); a woman with a prepregnancy body mass index from 19.8 to 26 should gain 25 to 34 lb (11.4 to 15.5 kg); and a woman with a prepregnancy body mass index from 26 to 29 should gain 15 to 24 lb (6.8 to 10.9 kg). The recommended weight gains during pregnancy are different for multiple gestations, e.g., a woman carrying triplets should gain about 50 lb [22.7 kg] during the course of her pregnancy.

Patient care

An essential component to anticipatory guidance and patient teaching is to encourage the woman's active participation in her own health maintenance and pregnancy progress. Health care providers describe to pregnant women common complaints related to normal physiological changes of pregnancy and suggest actions to minimize discomfort.

Disorders

Nausea and vomiting. See: morning sickness

Heartburn: Hormone-related delayed gastric emptying, cardiac sphincter relaxation, and stomach displacement by the growing uterus contribute to reflux. The use of low-sodium or combination aluminum hydroxide/magnesium hydroxide preparations is recommended for symptomatic relief. For severe, unresponsive heartburn, over-the-counter H2 blockers, such as ranitidine (Zantac) or famotidine (Pepcid), may be recommended.

Constipation: The woman should increase fiber and fluid intake. She also may use stool softeners.

Muscle cramps: The woman may relieve the so-called charley horse that occurs during sleep by dorsiflexing the foot of the affected leg. A calcium-phosphorus imbalance may contribute to increased frequency of this problem, although the causes are not clear. The woman can increase calcium intake by drinking the recommended daily quart of milk or by drinking a pint of milk daily and taking a calcium supplement with vitamin D.

Back pain: Growing anterior mass, shift in center of gravity, and increased lumbar curve contribute to backaches. To relieve discomfort, the pregnant woman should wear well-fitting, low-heeled shoes and perform exercises that increase abdominal muscle tone. See: pelvic rock; pelvic tilt

Dependent edema: Pedal edema is a common third-trimester complaint related to decreased venous return from the extremities. The woman is advised to rest frequently and to elevate her feet. She should report promptly any edema of the face, hands, or sacral area to facilitate early diagnosis and management of pregnancy-induced hypertension.

Varicose veins: Decreased venous return from the extremities and compression of vascular structures by the growing uterus aggravate any weakness in the vascular walls and valves. Varicosities often occur in the legs, vulva, and pelvis. The woman should avoid tight clothing and prolonged standing. Other preventive and therapeutic measures include wearing support stockings, resting in left Sims' position, and elevating the lower limbs during sleep.

Hemorrhoids: Temporary symptomatic relief may be obtained by Sitz baths and analgesic ointments. The woman also should be instructed in how to reinsert the hemorrhoid with a well-lubricated finger, holding it in place for 1 to 2 min before releasing the pressure. See: constipation

Vaginal discharge: A normal increase in vaginal discharge occurs during pregnancy. Common perineal hygiene usually is effective as a comfort measure; douching is contraindicated during pregnancy. The woman should contact her primary caregiver promptly if profuse, malodorous, or blood-tinged discharge occurs. See: vaginitis

Dyspnea: Shortness of breath occurs as the growing uterus presses on the woman's diaphragm. Elevation of the head and shoulders may provide some relief. The dyspnea disappears when lightening occurs.

Pruritus: The normal stretching of the skin may generate itching on the breasts, abdomen, and vulva. Pruritic urticarial papules and plaques of pregnancy is the most common benign dermatosis of pregnancy. Occurring in the third trimester, it usually resolves spontaneously after delivery. If severe, topical emollients, steriods, and, antihistamines may provide some relief. Use of an emollient lotion may be suggested; the patient is instructed to inform her primary caregiver if vulvovaginal itching occurs in conjunction with an increase or alteration in vaginal discharge. See: vaginitis

Nutrition

A woman's nutritional status before and during pregnancy is an important factor that affects both her health and that of her unborn child. Nutritional assessment is an essential part of antepartal care. In addition, the presence of pre-existing and coexisting disorders, such as anemia, diabetes mellitus, chronic renal disease, and phenylketonuria, may affect dietary recommendations. Substance abuse increases the risk of inadequate nutrition, low maternal weight gain, low-birth-weight infants, and perinatal mortality.

Dietary recommendations emphasize a high-quality, well-balanced diet. Increased amounts of essential nutrients (i.e., protein, calcium, magnesium, zinc, and selenium, B vitamins, vitamin C, folate, and iron) are necessary to meet nutritional needs of both mother and fetus. Most nutritional and metabolic needs can be met by eating a balanced daily diet containing approximately 35 kcal for each kilogram of optimal body weight plus an additional 300 kcal/day during the second and third trimesters. Because it is difficult to meet all the daily dietary recommendations, vitamin and iron supplements are recommended.

Considerations

Travel: Preparing for travel during pregnancy will depend upon the number of weeks gestation, the duration of the travel, and the method (i.e., auto, boat, bus, train, airplane).

Safety belts, preferably the combined lap and shoulder type, should be worn with the lap portion below the pregnant abdomen not across it. If nausea and vomiting of pregnancy is a factor, travel by sea isn't advisable. If anti-motion-sickness medication is used, it should be one approved for use during pregnancy (or antinausea wrist bands may be used). Travel during the last part of pregnancy isn't advised unless obstetrical care is available at the destination(s). It is important to have a copy of current medical records along when traveling. Travel abroad should be discussed with the obstetrician so that appropriate immunizations can be given. For travel in an area known to be endemic for malaria, certain drugs will be needed for prophylaxis.

CAUTION!

Live virus immunization should not be administered during pregnancy.

Working: Healthy pregnant women who are employed in jobs that present no more risk than those in daily life are encouraged to continue working if they desire until shortly before delivery.

Exercise: If the pregnancy is progressing normally, exercise should be continued. The amount and type of exercise is an individual matter. A woman who has exercised regularly before her pregnancy should experience no difficulty with continuing; however, a previously sedentary woman should not attempt to institute a vigorous exercise program such as long-distance running or jogging during her pregnancy. No matter what the type of exercise, it is important to remember that, with the progress of pregnancy, the center of gravity will change and probably prevent participation at the same level and skill as before pregnancy. Sports to avoid include water skiing, horseback riding, and scuba diving. In horseback riding, in addition to the possibility of falling from the horse, the repeated bouncing may lead to bruising of the perianal area. Scuba diving may lead to decompression sickness and bends and to intravascular air embolism in the fetus. Women who breast-feed their children should continue exercising if they maintain hydration and adequate breast support.

Sexual intercourse: Women who are experiencing normally progressing pregnancies need not avoid intercourse. Pregnant women should refrain from coitus if they have a history of preterm labor or premature rupture of membranes and if they are bleeding or have ruptured membranes.

Tests: Common tests include blood tests for nutritional or sickle cell anemia, blood type and Rh factor, rubella titers, syphilis, and serum alpha-fetoprotein for the presence of neural tube defects such as spina bifida. Additional testing may include determining HIV status and hepatitis immunity. Ultrasound may be used to determine age, rate of growth, position, some birth defects, and fetal sex. Chorionic villus sampling may be done early in pregnancy if the family history indicates potential for genetic diseases. Second trimester amniocentesis may be used to detect chromosomal abnormalities, genetic disorders, and fetal sex. In late pregnancy, nonstress tests, contraction stress tests, and fetal biophysical profiles may be done; amniocentesis may be done to evaluate fetal lung maturity. See: table

Vaccinations: Influenza vaccination is recommended during pregnancy

Pregnancy in adolescence: Although pregnancy among teenagers is decreasing in the U.S., about 7% of all American teenage girls still become pregnant in any given year, one of the highest rates of teen pregnancy in developed countries. Sociocultural factors are believed to contribute to the high incidence of pregnancies among this population. Demographic data indicate that teen pregnancy is more likely to be associated with being single, having low socioeconomic status, and lacking social support systems. Pregnant teenagers are believed to be at high risk for some complications of pregnancy; if, however, they seek prenatal care early and consistently cooperate with recommendations, the risk is comparable to that for other age groups. Clinical data identify a common pattern of late entry to the prenatal care system, failure to return for scheduled appointments, and noncompliance with medical and nursing recommendations. As a result of these behaviors, adolescents are at higher risk for pregnancy-related complications, such as iron-deficiency anemia, pregnancy-induced hypertension, preterm labor and delivery, low birthweight newborns, and cephalopelvic disproportion. Other health problems seen more commonly in pregnant adolescents include sexually transmitted diseases and substance abuse.high-risk pregnancy;

Mature pregnancy: A growing number of women are experiencing their first pregnancies after age 35. The incidence of fetal demise among this population is 6:1000 births, double the rate for women under 35. Many factors may contribute to the increased risk, including pre-existing and coexisting conditions, such as diabetes mellitus, hypertension, and uterine fibroids. Mature women are identified as being at higher risk for spontaneous abortion, preeclampsia, abruptio placentae, placenta previa, gestational diabetes, cesarean birth, and chromosomal abnormalities such as Down syndrome. Multiple-gestation secondary assisted reproduction also may be a factor in fetal loss.

Pregnancy after menopause: Very rarely, postmenopausal women have become pregnant through embryo donation and have successfully carried the pregnancy to term delivery. Prior to undergoing this procedure, the women had been undergoing hormone replacement therapy. Previously, it had been assumed that the postmenopausal uterus would not be capable of supporting the growth and development of an embryo. Pregnancies in older women are considered high risk for reasons similar to those related to mature pregnancy. Late in the third trimester, the woman may be instructed to keep a fetal activity record and undergo regularly scheduled nonstress tests.

abdominal pregnancy

Ectopic gestation in which the embryo develops in the peritoneal cavity. Synonym: abdominocyesis See: ectopic pregnancy

ampullar pregnancy

Ectopic implantation of the zygote in the ampulla of a fallopian tube; 78% of all ectopic pregnancies occur in this site.

bigeminal pregnancy

Intrauterine twin gestation.

biochemical pregnancy

A pregnancy that is confirmed by laboratory tests of blood or urine but cannot be seen using contemporary imaging techniques.

cervical pregnancy

Pregnancy with implantation of the embryo in the cervical canal.

clinical pregnancy

Any conception that is detected by ultrasonography or serum hormone levels, whether or not the pregnancy is healthy or likely to progress to delivery of a newborn child. Examples of clinical pregnancies include healthy singleton, twin, and other multiple pregnancies; ectopic pregnancies; and threatened miscarriages, among others.

cornual pregnancy

A rare type of ectopic pregnancy (found in about 2% to 4% of all ectopic pregnancies) in which implantation takes place in one of the horns of the uterus. The uterine horn may rupture between the 12th and 16th week of gestation, causing life-threatening shock. Traditionally, cornual pregnancies have been managed with laparotomy and hysterectomy, although conservative management strategies are employed occasionally.

SITES FOR ECTOPIC PREGNANCY

ectopic pregnancy

Extrauterine implantation of a fertilized ovum, usually in the fallopian tubes, but occasionally in the peritoneum, ovary, or other locations. Ectopic implantation occurs in about 1 of every 150 pregnancies. Symptoms usually occur between 6 and 12 weeks after conception. Synonym: extrauterine pregnancy See: illustration; pregnancy

Symptoms

Early complaints are consistent with those of a normal pregnancy (i.e., amenorrhea, breast tenderness, nausea). Pregnancy test results are positive owing to the presence of human chorionic gonadotropin (hCG) in blood and urine. Signs and symptoms arise as the growing embryo distends the fallopian tube; associated complaints include intermittent, unilateral, colicky abdominal pain. Complaints associated with tubal rupture include sharp unilateral pelvic or lower abdominal pain; orthostatic dizziness and vertigo or syncope; and referred shoulder pain related to peritoneal irritation from abdominal bleeding (hemoperitoneum). Signs of hypovolemic shock may indicate extensive abdominal bleeding. Vaginal bleeding, typically occurring after the onset of pain, is the result of decidual sloughing.

Locations

Abdominal: The incidence of pregnancy in the abdominal cavity with the conceptus attached to an abdominal organ is between 1:3000 and 1:4000 births. Ovarian: Conception and implantation within the ovary itself occurs in approximately 1 in 7,000 to 1 in 50,000 pregnancies. Tubal: Ninety to 95% of ectopic pregnancies occur in the fallopian tube; of these, 78% become implanted in the uterine ampulla, 12% in the isthmus, and 2% to 3% in the interstices.