It’s not just women who have biological clocks, British researchers reported on Wednesday.
As men get older, it takes them longer to father a child, the team at the University of Hull reported.
Doctors have long known that the older a woman is, the more trouble she will have conceiving. Men can, at least theoretically, father children until they die.
But a study of more than 1,200 pregnant women shows it is not always easy.
Mohamed Hassan and Dr. Stephen Killick questioned the women about everything from whether they smoked to how long it took them to become pregnant. The time it took them to get pregnant, they found, became noticeably longer when their partners were 45 or older.