Tech + Health

06.29.14

The Crumbling Post-35 Pregnancy Myth

The prevailing myth that women can’t and shouldn’t get pregnant after the age of 35 is finally starting to crumble. Science shows women can safely deliver healthy babies into their 40s.

When I was 40 and pregnant with my youngest child, I remarked to my husband one day, “You know, when this baby graduates from college, I’ll be 62 years old.”

My oldest daughter Kate, who was 5 at the time, must have overheard me, because the next day she announced, “You know, Mom, when the baby gets out of college, you’ll be almost dead!”

Maybe not.

A new study finds that women who had their last child when they were 33 or older lived longer than those who had their last child by 29. It doesn’t necessarily mean one causes the other—it’s possible that being healthy enough to get pregnant later also causes longevity—but it’s encouraging news for those of us who waited until our late 30s to have children.

That news has been coming more quickly in recent years. As I noted in my book The Impatient Woman’s Guide to Getting Pregnant, the scary statistic that one out of three women over 35 will not be pregnant after a year of trying comes from an analysis of French birth records between 1670 and 1830. Studies of more modern populations find fairly high fertility in a woman’s late 30s. About 80 percent of women 35-39 will get pregnant naturally in a year of trying. That’s barely different from the 85 percent of under 35’s who will succeed.

Other recent good news for older women and fertility comes from an unlikely source: statistics from in vitro fertilization (IVF) clinics. Until just a few years ago, IVF success rates for older women were depressingly low. As of 2011—the most recent national statistics available—only 27 percent of women in their late 30s had a baby after one IVF cycle, compared to 40 percent of those under 35. For women spending upwards of $10,000 in a last-ditch effort to have a baby, such a reduction in chances can be devastating.

But that was 2011. IVF clinics can now identify chromosomally normal embryos—those that will grow into a healthy baby—through a procedure called comprehensive chromosome screening (CCS). Pregnancy rates after the transfer of normal embryos can top 70 percent. In a study published in March in Fertility and Sterility, researchers from Reproductive Medicine Associates of New Jersey found that more than half (57 percent) of embryos from women in their late 30s were chromosomally normal. Almost all 35 to 39-year-old women—92 percent—had at least one normal embryo to transfer after a single IVF cycle.

Although most women will not need IVF, such studies are useful. They eliminate many of the extraneous factors that can bias studies of natural conception, such as older couples having sex less often. Even so, the IVF and natural conception studies come to the same conclusion: Women’s fertility is fairly high through their late 30s. The real reductions come only after age 40; 42 percent of 40-year-old women’s embryos were normal, which sunk to 12 percent by age 44. The percentage without any normal embryos to transfer was virtually unchanged between the ages of 29 and 37, rose slightly for 38-to-40-year-olds, and was not over 50 percent until age 44.

About 80 percent of women 35-39 will get pregnant naturally in a year of trying. That’s barely different from the 85 percent of under 35’s who will succeed.

IVF with chromosome screening virtually eliminates the risk of miscarriage and chromosomal abnormalities such as Down’s syndrome, both of which are higher among older women who conceive naturally. Even so, these risks are not as high as one might expect. At early genetic testing, 99 percent of fetuses are normal when a woman is 35, and 97 percent at 40. Miscarriage rates rise from about 15 percent for those under 35 to 27 percent in a woman’s late 30s.

Many women who are trying to get pregnant in their late 30s and early 40s didn’t necessarily want to wait that long, but met their partners later in life. Others postpone motherhood until they are financially stable. The popular assumption that most over-35 mothers are “driven career women” is a myth with a strong undercurrent of misogyny around women’s role in the workplace. Every story is different.

Whatever their reason for waiting, both women and their children can reap numerous benefits from later motherhood. Women who wait are often more established in their careers, more mature, and able to provide more for their children once they arrive. One analysis found that every year a woman postpones having children leads to a 10 percent increase in earnings.

I cannot imagine what it would have been like to have a baby in my 20s, when I was in graduate school and completing a postdoctoral fellowship. I made between $14,000 and $23,000 a year and had no job security. I also didn’t meet my husband until I was 30, after my first marriage collapsed under the pressure of trying to find two academic jobs in the same place. As a result, our first child did not arrive until I was 35, with the others following at 38 and 40.

Despite my fears around my supposedly declining fertility, this delay produced mostly benefits: I’d already gotten tenure and written my first book, we’d traveled and grown more mature, and we had the money to pay for day care, a house in a good school district, and the seemingly endless smaller items from baby gear to sports teams. Sure, we were tired when they were babies, but who isn’t? I do sometimes wish I’d had children earlier when I had more energy, but overall the benefits of later motherhood have far outweighed the costs.

And if I’m lucky, I’ll live to see my youngest graduate from college—and won’t be “almost dead” after all.