Skip to main content

Biological clockGetty Images/iStockphoto

An American academic has some refreshing news for 30-something women who are growing tired (at best, and irritated at worst) at the barrage of messages about the deafening biological clock that should be ticking in their ears.

Jean Twenge, a prominent psychology researcher at San Diego State University in California, writes that the situation may not be as depressing as it appears – and that women who haven't yet found a mate or who don't yet have a plan need not slap a spinster sticker on their forehead at the ripe old age of 36.

In a piece titled How Long Can You Wait To Have A Baby? in the Atlantic, Twenge shares her own post-divorce panic of a decade ago and her personal research into whether women's fertility takes a nosedive at the age of 35 (she now has three children with her second husband; the last was born when she was 40.)

For starters, she found that much of the information circulating out there is based on received wisdom, not great science.

"The widely cited statistic that one in three women ages 35 to 39 will not be pregnant after a year of trying, for instance, is based on an article published in 2004 in the journal Human Reproduction," she writes. "Rarely mentioned is the source of the data: French birth records from 1670 to 1830. The chance of remaining childless – 30 per cent – was also calculated based on historical populations."

Her salvo comes at at time when educators and medical professionals are hoping to spread the word about declining fertility, and urging women and men to consider their plans early. Sites such as UBC's Fertility Choices avoids a lecturing tone while trying to address stubborn, widely held beliefs: For example, more than 90 per cent of women believe that a woman can get pregnant with her own eggs in one round of IVF until about the age of 50. (Wrong)

But at the younger end of the spectrum, however, Twenge finds evidence that the message may be overstated for women in their late 30s.

One 2004 study she found looked at the chances of pregnancy among 770 European women and found that with sex at least twice a week, 82 per cent of 35-to-39-year-old women conceive within a year, compared with 86 per cent of 27-to-34-year-olds, she writes. In other words, almost identical.

Similarly, another followed 2,820 Danish women and found that of women having sex during their fertile times, 78 per cent of 35-to-40-year-olds got pregnant within a year, compared with 84 per cent of 20-to-34-year-olds. A new study out this month finds that among 38- and 39-year-olds who had been pregnant before, 80 per cent of white women of normal weight got pregnant naturally within six months, she reports. She adds that the percentage was lower among other races and among the overweight.

The news remains not good for women as they pass the 40-year milestone, so her bottom line:

"… plan to have your last child by the time you turn 40. Beyond that, you're rolling the dice, though they still come up in your favour."

Interact with The Globe