The Truth About Pregnancy Over 40

More than 100,000 Americans give birth in their 40s each year, but what does that mean for the health of their pregnancies and their babies?

Reyhan Harmanci, who is currently pregnant with her second child, photographed outside in Brooklyn.
Credit...Celeste Sloman for The New York Times

This story was originally published on Nov. 12, 2019 in NYT Parenting.

At some point in elementary school, I understood something about my mother: She was older than the other moms. Every now and then, I would write her age on a form or talk about the year she was born, and a classmate would loudly exhale at the response. “Man,” she would say, “that’s ANCIENT.”

Indeed. My mother was a whopping 29 when she got pregnant, and 30 when she gave birth to me.

This situation came to mind earlier this year, when my father-in-law expressed unprompted concern about the possibility of my husband and me having a second child at my “advanced age” of 40. We were courting medical disaster, he said, for myself and for the baby.

My first response was fury — O.K., boomer — but did he have a point? In 2019, the Centers for Disease Control and Prevention announced that while the birthrates for women under 40 had been declining for years, those for women in their early 40s were increasing — by 3 percent every year since 1982. The average age of first-time mothers in the United States is now 26 — up from 23 in 1994. And in Manhattan, near where I live, it’s 32.

Risk is a squishy concept, and it is tricky to square scientific research with one’s personal experience, but there are undoubtably certain hazards specific to what, until recently, was called a “geriatric pregnancy.” To put those issues into perspective, I spoke with six experts to learn about the unique concerns that may arise with having a child after 40.

Credit...Celeste Sloman for The New York Times

This is probably the best-known part of the aging equation. The fact is, eggs gradually decline in number and quality as you get older. If you’re over 35, you’re considered to be of “advanced maternal age” — with fertility starting to drop most significantly around 32, according to the American College of Obstetricians and Gynecologists, and taking a particularly deep nose dive around 37. “By age 44, the chances of spontaneous pregnancy approach zero,” said Dr. Jane van Dis, M.D., an ob-gyn practicing in Burbank, Calif.

Of course, reproductive technologies such as in vitro fertilization can help some couples skirt those numbers, but even those efforts can become less successful with age. According to a 2016 report from the C.D.C., one in vitro fertilization cycle has a 36 percent chance of successfully impregnating a woman under 35, whereas it has about a 22 percent chance for women between 38 and 40, about a 13 percent chance for those 41 or 42, and about a 6 percent chance for women over 42.

[Read more about fertility here.]

Miscarriages and stillbirths can happen at any age, but the chances increase as you get older. Pregnancy losses that happen before 20 weeks — which are called miscarriages; anything later is considered a stillbirth — are almost always caused by chromosomal problems in the embryo, which are more likely in older eggs. For this reason, according to Dr. van Dis, women between 40 and 44 have a 33 percent chance of miscarriage. Across all pregnancies, miscarriage risk is believed to be closer to 10 to 20 percent, though estimates can vary. It is possible these percentages may be higher, because, for instance, many women who miscarry do so before they know they are pregnant and may not report it.

Evidence also suggests that pregnant people in their 40s are at higher risk of stillbirth. The reasons are a bit murky — though in a 2008 review of studies, researchers suggested that the higher incidence of conditions like high blood pressure during pregnancy or gestational diabetes among older mothers may be at least partly to blame.

Because longer gestational times can increase the risk of stillbirth, many doctors won’t allow a woman over 40 to go into labor past her due date. Generally, she will be given a planned induction.

As you age, your chances of developing certain cardiovascular problems like high blood pressure and heart disease increase. This is one of the reasons women over 40 are at higher risk for pre-eclampsia (high blood pressure and protein in the urine during pregnancy, which can be life-threatening) and gestational diabetes (abnormally high blood sugar during pregnancy). These conditions can create a host of problems for both mother and baby — including low (or abnormally high) birth weights and premature deliveries.

Another big problem is an increased chance of developing placenta previa, a condition in which the placenta either partly or fully covers the cervix. Across all pregnancies, one in 200 will develop the condition, with evidence suggesting a much higher risk for women 35 or older. Placenta previa is dangerous, and can increase the risk for premature labor and stillbirth.

This was probably the biggest surprise to me: Research suggests that the older a new mother is when she has her first child, the higher her risk for breast cancer. According to Louise Brinton, Ph.D., who was formerly chief of the Hormonal and Reproductive Epidemiology Branch at the National Cancer Institute, women who have their first child after 40 may be at slightly higher risk of developing breast cancer in the decade or so following childbirth than those who gave birth before they were 20. “The simplistic view is that as you age, your cells are constantly changing, and a heavy dose of hormone can promote them into cancer,” Dr. Brinton said.

How this phenomenon translates into absolute, rather than relative, risk, however, is a bit thorny. A large study published in 2018, for instance, found that among women who had children between 34 and 47, 2.2 percent developed breast cancer within three to seven years after they gave birth (among women who never had children, the rate was 1.9 percent). Over all, according to the American Cancer Society, women between 40 and 49 have a 1.5 percent chance of developing breast cancer.

To confuse things further, studies have also shown that a history of childbirth may have a protective effect against breast cancer later in life, said Hazel Nichols, Ph.D., an associate professor of epidemiology at the University of North Carolina Gillings School of Global Public Health and one of the authors of the 2018 study. So the slightly increased risk of breast cancer following a birth later in life may be balanced by having more children in general.

The best thing you can do, Dr. Brinton said, is to make sure that your doctor is aware of this risk and that you are regularly screened with mammograms.

Once again, the older an egg, the more likely it is to have chromosomal issues, which can increase your child’s risk for certain birth defects. For women who get pregnant at 25, the risk for Down syndrome, the most common chromosomal condition, is about one in 1,250; at age 40, that risk jumps to about one in 100.

Of course, noninvasive blood tests for chromosomal issues like Down syndrome allow you to get information about your child’s genetic makeup as early as 10 weeks.

There is also some, if limited, evidence that older fathers may pose certain risks to their offspring. A review published in 2019, for instance, found that babies born to fathers 45 or older were at higher risk for certain complications like low birth weight, a low Apgar score (a quick test to gauge a baby’s well-being one to five minutes after birth) and premature birth. They also seemed to be more likely to develop autism, schizophrenia and obsessive-compulsive disorder than the children of men who were younger. It is important to note, however, that all such studies were observational, so more research is needed.

What, then, to make of all of this? The most optimistic clinician I spoke to was Dr. James Grifo, M.D., Ph.D., program director at the NYU Langone Fertility Center. He pointed out that while “pregnancy is one of the riskiest states that most women experience in their lives,” the odds of a calamitous event are still low. “The average age of my patient is 39, and obstetrically, they do quite well,” he said. “Age is not a reason not to try if you want a baby.”

Over and over, I found myself having two conversations with experts: One about what they knew from their patients or their research, and another about the choices they made about when to have children on their own.

Dr. Brinton, for instance, who had a daughter when she was 42, said that her biggest issues were “societal” rather than medical. “I was always the older mother,” she said. “When I would go to school, I would be asked if I was her grandmother. When it comes from a child, it’s a stab in the heart.”

Dr. van Dis, who had twins at 39, said she wished she had children when she was younger, but not because of the health risks. She put off having children earlier because of her medical career and her then-husband’s ambivalence toward starting a family — and now she is divorced. “I would have told my younger self that it’s better to be a single mom than to partner with someone who is not committed to you, just because you think you won’t be able to have a family if you don’t have a partner,” she said.

Is it responsible or smart to try to have kids at 40? Psychological studies tell us that humans have trouble imagining themselves as subject to bad outcomes, which may be why we persist in rolling the dice. Joan Didion tells us that “anything worth having has its price.” What my father-in-law didn’t know is that when he sent that note, I was already pregnant.

Reyhan Harmanci is deputy head of programming at Gimlet.