LONDON--Human fertility starts to decline earlier than previouslybelieved, new research suggests, providing the most precise insightyet into when biological clocks start ticking loudly--at age 27 forwomen and 35 for men.
Until now, it was thought that women's fertility starts to dropsignificantly in the early 30s, with a big plunge after 35. But thenew study indicates that, on average, female fertility begins itsmeaningful slide at age 27.
And while the decline in human fertility tied to aging hadtraditionally been attributed to the female factor, the study,published today in the journal Human Reproduction, showed that men'sfertility starts dwindling after 35.
Nevertheless, experts said the findings should not raise undueconcern. The results mean it may take a month or two longer toconceive than it does for younger people, they said. The ages atwhich declines were seen are only averages and there is a wide rangein fertility at any specific age.
"Certainly very young women in their early 20s are more fertilethan women in their late 20s and early 30s. But I suspect that thefertility of those women who are around 30 is high enough that itdoesn't give them a real cause for concern or worry up to the age of35," said Dr. Chris Ford, a researcher at the University of Bristolin England who studies fertility and age, but was not involved withthe study.
The study involved 782 healthy couples from across Europe who wereusing only the rhythm method of family planning.
The study also found that men's fertility dropped after 35.Previous research had hinted that male fertility starts to decline inthe 40s or 50s.
The study found that while a 35-year-old woman with a partner thesame age had a 29 percent chance of getting pregnant in one month,her chances dropped to 18 percent if her partner was 40.
No decline in male fertility was seen before age 35, and the man'sage only seemed to matter when the woman passed 35, the study found.
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