A year ago, the mosquito-borne Zika virus was only beginning to reveal itself as a threat to pregnant women and their unborn babies.

In September, Ms. Wilde casually announced the gender of her unborn child in an anti-Trump tweet, Elle magazine reported at the time.

“Furthermore, such a defeat invites additional challenges to Ohio’s strong legal protections for unborn life,” said Mr. Kasich in his veto message.