I always had a hunch that the “research” that proves we are all slowing rolling away from fertility once we turn 30 was a crock of shit. It turns out – it may not be a crock of shit, it’s just really, really old. Atlantic writer Jean Twenge claims in an essay this week that the “decline in fertility over the course of a womanâ€™s 30s has beenÂ oversold.” Apparently, this declining fertility fear is also based in really old research:
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 journalÂ Human Reproduction. Rarely mentioned is the source of the data: French birth records from 1670 to 1830. The chance of remaining childlessâ€”30Â percentâ€”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. Most people assume these numbers are based on large, well-conducted studies of modern women, but they are not.
Twenge found newer studies that prove there is not such a vast decline in fertility that we once feared there was. Biostatistician David Dunson from Duke University, found that:
[I]ntercourse two days before ovulation resulted in pregnancy 29 percent of the time for 35-to-39-year-old women, compared with about 42 percent for 27-to-29-year-olds. So, by this measure, fertility falls by about a third from a womanâ€™s late 20s to her late 30s. However, a 35-to-39-year-oldâ€™s fertility two days before ovulation was the same as a 19-to-26-year-oldâ€™s fertility three days before ovulation: according to Dunsonâ€™s data, older couples who time sex just one day better than younger ones will effectively eliminate the age difference.
What? This isn’t nearly as doom-and-gloom as we’ve been led to believe. I spent four years trying to conceive my first child in my early thirties. My second was conceived when we were less than careful once. I was 39. I’ve heard plenty of stories of women having an easy time conceiving in their late thirties – but always thought they must just be anecdotal. It seems that our bodies must be evolving to accommodate our modern lifestyles. Maybe we shouldn’t be basing our fertility fears on evidence obtained prior to the 1800′s.
The truth is, we could probably find a study done that would back up any hypothesis we have about age and fertility – there are certainly enough out there. But I have to admit it is refreshing to see some evidence that basically says, Chill out. Your eggs aren’t shriveling up as we speak. Her essay is definitely worth reading.Â As a woman who gave birth to her first child at 37 and her second at 40 – both totally healthy – I assure you that sometimes a woman’s body can still make babies well into her thirties.