Your Clock is NOT Ticking

You know they say your (female) fertility starts sliding at 30 and dives off a cliff at 35? Well here’s news from The Atlantic:

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. Rarely mentioned is the source of the data: French birth records from 1670 to 1830. The chance of remaining childless—30 percent—was also calculated based on historical populations.

In other words, millions of women are being told when to get pregnant based on statistics from a time before electricity, antibiotics, or fertility treatment.

- Jean Twenge

So what are the facts?

Surprisingly few well-designed studies of female age and natural fertility include women born in the 20th century—but those that do tend to paint a more optimistic picture. One study, published in Obstetrics & Gynecology in 2004 and headed by David Dunson (now of Duke University), examined the chances of pregnancy among 770 European women.

It found that with sex at least twice a week, 82 percent of 35-to-39-year-old women conceive within a year, compared with 86 percent of 27-to-34-year-olds. Another study, released this March in Fertility and Sterility and led by Kenneth Rothman of Boston University, followed 2,820 Danish women as they tried to get pregnant. Among women having sex during their fertile times, 78 percent of 35-to-40-year-olds got pregnant within a year, compared with 84 percent of 20-to-34-year-olds. [Bolding mine]

A study headed by Anne Steiner, an associate professor at the University of North Carolina School of Medicine, the results of which were presented in June, found that among 38- and 39-year-olds who had been pregnant before, 80 percent of white women of normal weight got pregnant naturally within six months (although that percentage was lower among other races and among the overweight). “In our data, we’re not seeing huge drops until age 40,” she told me.

Twenge finishes by referring us to the this Saturday Night Live clip (warning: it’s Saturday Night Live), in which four actresses complain about being pressured to have babies.

Eleven years later, these four women have eight children among them, all but one born when they were older than 35. It’s good to be right.

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14 thoughts on “Your Clock is NOT Ticking

  1. There’s still the issue of increased risk of Down’s syndrome when you give birth for the first after 35.

  2. More, I think, that if you start having kids young, you can be done by 35 and lower the risk of Down Syndrome. Though I know several cases of Down Syndrome where the mother was in her 20s, the risk is higher at the older ages.

  3. “… found that among 38- and 39-year-olds who had been pregnant before, 80 percent of white women of normal weight got pregnant naturally within six months”

    Um, we are assuming that this statistic does not apply to our not-yet-married singles in their mid to late 30s.

  4. I think that the fertility issue is bigger than she makes out: for those women who have trouble conceiving (even if it’s, say, 10% of all women under 40, the same across all age subgroups), fertility treatments are much more successful if one is under 35. And you can’t know if you’re going to be in that 10% unless you try to conceive. But I do think that the panic could be less than it generally is nowadays.

  5. Well, she does say exactly that in the original article. She says most of what doctors say about being under 35 comes from the fertility clinics. But if you don’t have fertility issues, then it doesn’t apply.

  6. I guess without testing it out, you have no way of knowing if you fall into the “fertility issues” bucket. And since it’s not an insignificant percentage who do, it’s not an unreasonable source of worry.

  7. No, but there are signs of fertility issues. If you’re not showing any, there’s a reasonable assumption that you haven’t got any.

  8. AGE OF MOTHER % Down’s Syndrome Children
    less than 30 less than 1 in 1,000
    35 1 in 400
    40 1 in 105
    42 1 in 60
    44 1 in 35
    46 1 in 20
    48 1 in 12
    SOURCE: Power Aging (page 268) by Gayle Olinekova, published in year 1998

  9. There are signs of SOME fertility issues. Many if not most cases of infertility are idiopathic, meaning there’s no identifiable cause. Yes, if you have the signs of PCOD, they are identifiable. But many people are blindsided by infertility: they have regular cycles, they have a fertile mother and sisters, and they have no reason to expect fertility problems.

    And we’re not even talking about male factor infertility here. And children of older fathers may be more likely to develop autism or schizophrenia. Woohoo! (NOT)

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