echo boom
/ˈɛkəʊ buːm/originally US
noun
A period of marked increase in the birth rate resulting from children born in a previous baby boom themselves becoming parents; specifically that between the late 1970s and early 1990s, when children of the post-Second World War baby boom became parents.
Origin
1970s; earliest use found in Advocate (Newark, Ohio). From echo + boom, after baby boom.