SALT LAKE CITY — When Illinois Sen. Tammy Duckworth gives birth in April, she'll be the first U.S. senator to have a baby in office. She'll also be 50 years old.
In medical lingo, this makes Duckworth's pregnancy "geriatric," or since this is her second child, "elderly multigravida." But in widely shared photos of Duckworth working out, it's clear that the Purple Heart recipient is neither geriatric nor elderly.
The kinder term is "advanced maternal age," a category that describes an increasing number of American women who are having babies in their 40s and 50s.
In 2016, 786 babies were born in the United States to moms 50 or older, according to a report released in January by the National Center for Health Statistics. Twenty years ago, the number of women who gave birth at 50 or older was 144.
The number of women giving birth in their 40s has climbed steadily since 1997, as well, even as the birth rate for teens has declined. In 2016, the birth rate for women ages 40-44 was 11.4 births per 1,000 women, up 4 percent from 2015, according to government statistics. This was the highest birth rate for women in their 40s since 1966. Conversely, 2016 saw the continued decline of women giving birth in their 20s.
The increase in the number of women giving birth around the time of menopause is enabled in part because of advances in assisted reproduction, including IVF and egg freezing. Using donated or frozen eggs, there is no age limit on when a healthy woman can be pregnant, as evidenced by a woman in India who in 2016 gave birth to a child at age 72.
But some women in their 40s — and occasionally, in their 50s — can conceive without medical assistance.
Having a toddler underfoot in your early 20s, however, is quite different from having one in the house at 50 or 72. The younger mother may have more energy, but the older one often has more wisdom and money. But the experience of midlife pregnancy is largely positive for women who have experienced it, researchers say.
And women have been having babies at midlife as long as they've been having babies.
Why some wait
Duckworth, a first-term Democrat, is an Iraq War veteran who lost both legs in 2004 when a rocket-propelled grenade hit the helicopter she was flying. She has spoken candidly about her struggles to conceive, and her first child, a girl, was born three years ago after a decade of trying.
"This was a struggle to get pregnant," Duckworth told NBC News. "It is a struggle to be a working mom and to try to deal with all of these issues, and it was a very long journey for us to get to the point where we can have this second child, and we're just very, very blessed that we can do it. But yet, there are millions of women all across this country who continue to struggle."
The average age of menopause is 51, and the average at which a woman can have a healthy pregnancy and birth without fertility treatments is 41 years, said Dr. Erica B. Johnstone, a gynecologist and reproductive endocrinologist who teaches at the University of Utah Center for Reproductive Medicine.
Women who use donated eggs because they have trouble getting pregnant or carrying a pregnancy to term account for the majority of midlife pregnancies achieved through in vitro fertilization, Johnstone said.
Some women have to delay pregnancy because of a health issue, such as treatment for cancer. These women can have eggs removed and frozen for later use.
But an increasing number of women are opting to delay pregnancy because they are not yet married or simply focusing on their careers. When these women freeze their eggs for later use, it's called "social freezing." Some companies, including Facebook and Apple, are even making egg freezing an employee benefit.
It's not yet known how long a frozen egg by itself remains viable, but last year, a baby that was frozen as an embryo 24 years earlier was born in Tennessee.
And, Johnstone said, "There doesn’t appear to be an upper limit on the age which it is physically possible to become pregnant."
The woman in India who gave birth at 72 after trying for 46 years, however, shows that there may be an upper limit on the age at which parents can easily raise the child.
"Since he's been crawling, I'm on my hands and knees, and it's hard. My body can't take it. It's been harder than I thought," Daljinder Kaur told a reporter for Cover Asia Press.
In Utah, 80 women aged 45 or older gave birth in 2016, up from 62 in 2015 and 70 in 2014, according to vital statistics reports from the Utah Department of Health.
Women who become pregnant in their 40s and 50s have an increased risk of complications that include gestational diabetes, pre-eclampsia, cesarean delivery and pre-term delivery of a baby with low birth weight. These risks increase with the mother's age, but they vary, depending on the woman's overall health, according to a 2015 study on social freezing published in the Canadian Medical Association Journal.
Most of these conditions occur because blood vessels change as we age, becoming thicker and stiffer, and pregnancy causes increased blood flow, said Johnstone.
"Pregnancy is a great stress test for a woman," she said. "If you want to see what kind of shape a person's heart is in, you can have them get on a treadmill and do a stress test. Pregnancy does the same thing."
About half of women who give birth around or after 50 will develop pre-eclampsia, a potentially dangerous rise in blood pressure, during the pregnancy. But while some may have it in the second trimester, others may not develop it until the final weeks of the pregnancy. Such complications typically end when the baby is delivered, although one study found a slightly increased risk of heart defects in babies whose mothers developed pre-eclampsia early in the pregnancy.
As for the babies born to older mothers, recent studies suggest that they ultimately seem to fare as well as children born to younger women, and in some cases, fare better. One study, in Sweden, found that children of older mothers were fitter, taller and healthier than those born to younger women.
These outcomes, however, could partially be explained by the fact that most women giving birth through assisted reproductive technology tend to have socioeconomic advantages. (Doree Shafrir of BuzzFeed News recently analyzed what five couples spent in their quest to become parents; those using assisted reproductive technology spent between $15,000 and $200,000.)
Hoping for health
Elizabeth Gregory, an English professor at the University of Houston, has studied women who have children later in life, and also had children late herself. Gregory had her first child at age 39 and at 48, adopted a 1-year-old. Now 60, she has a 20-year-old in college and a 13-year-old at home.
“The whole field of parenthood is shifting, and it makes sense, given the radical new technologies and also the fact that people live longer and have a whole different way of organizing their lives than formerly,” Gregory said.
But, she noted, what’s most significant is that the age at which women have their first child is later than in the past. “Historically, people often had children in their late 40s; it’s just it wasn’t their first child, but their 12th,” she said.
Also, “most people having babies in their 40s now are doing it through egg donation; previously, it would be an accident. My grandmother, who was born when her mother was 46 — they thought she was a tumor.”
In researching her book on later-life pregnancy, “Ready,” Gregory found that many women don’t believe having children early makes sense if they want a career. They expect they’re going to live long enough to see their child (or children) graduate from college and get married. And chasing after kids can help keep you fit, and young psychologically. “I know a lot about anime,” she said.
What Gregory doesn't yet know is how her late start to parenthood will affect her daughters as she ages. Older parents run the risk of setting their children up to be caregivers when they're just starting families or careers. And their children may not have the support of active and involved grandparents as they begin their own families.
“If I became ill, I would hope that my husband would take care of me, not my children," Gregory said. "If we both became incapacitated, our children would have to figure that out. The good side of it is that we would hope they could draw on more resources so they wouldn’t be stuck in a situation where they had to give all the care."
But, she acknowledged, “You’re betting on your ongoing health and longevity” when you have children later in life and hope to be around for their graduations, weddings and grandchildren.
As for the social implications of later-life pregnancy, there aren’t enough women having babies in their 50s to have much of a measurable effect, although that may change if social freezing takes off. But the women who are giving birth later in life are already having an effect on the culture by showing others that it’s possible.
“There’s a lot of messaging out there,” Gregory said. “(Women) clearly have an expectation that they can do this later if they want to; they have a sense of the possibilities out there. Which may or may not be not be correct. If you delay in your 20s and have children in your 30s, you’re probably going to be fine. If you think you’re going to delay until you’re 50, you might succeed.”
Reducing the risks
Most women wanting to get pregnant in midlife don't face the physical challenges of Duckworth, who has two prosthetic legs.
However, Dr. Nathan Fox, a maternal fetal medicine specialist in New York City, said women who want to have a child in their 40s or 50s should be as healthy as possible before getting pregnant, both for their own sake and the sake of the child.
“Generally, if a woman comes into the pregnancy healthy — she doesn’t smoke, she’s not obese, she doesn’t have heart disease, she’s fit, she’s well — and the only 'issue' she has is that she’s over 45, generally the outcome is going to be very good for her," Fox said.
“She may get high blood pressure, she may get (gestational) diabetes, she may have a C-section, but typically, she’s going to come out doing well, as is her baby. That’s what most of the research shows,” he said.
If a woman has health problems before conceiving, then her health issues are compounded during the pregnancy, and the baby may also be at risk of premature delivery and low birth weight, which can lead to health problems, at least temporarily, for the child.
Younger parents may have more energy; older parents may have more wisdom, experience and financial resources. But, Johnstone said, “There’s no one right age for everyone to have a child.”
Giving birth after 50, “requires serious consideration of all the pros and cons, both for the mother and the baby. I definitely have concerns about (getting pregnant) over the age of 50. I also would never say that it’s something no one should consider.”