When Senator Lindsey Graham, Republican of South Carolina, proposed a national ban on abortions after 15 weeks of pregnancy, the bill sparked controversy across the political spectrum. But few spoke of its potential impact on the growing number of women who are having children in their 30s.
The proposed ban would allow exceptions to save a woman’s life and for some pregnancies resulting from rape and incest, but it notably lacks exceptions for fetal abnormalities. As such, it would sharply restrict options for the growing numbers of older women with pregnancies that are long-delayed and much wanted — but also come with a greater risk of conditions like Down syndrome.
The median childbearing age in the United States has increased in recent decades, reaching 30 in 2019, up from 27 in 1990. But older mothers are more likely to conceive fetuses with chromosomal abnormalities, and the test most commonly used to detect those disorders can only be performed after a pregnancy is 15 weeks along, beyond Mr. Graham’s proposed window for abortion.
Some anatomical anomalies, too, cannot be diagnosed until later in pregnancy. Older mothers are also more likely to enter pregnancy with health conditions that can worsen as gestation progresses and can require termination to save the woman’s life or prevent disability.
“There have been large declines in births to women in their 20s in every single demographic group,” Dr. Morse said. And every demographic group, with the exception of Native American and Alaska Native women, has seen an increase in birthrates among women aged 35 to 39, she said.
Mr. Graham’s bill, which is not expected to pass in a Congress narrowly controlled by Democrats, has been controversial even among Republicans who oppose abortion, and several Republican senators told reporters that the issue is best left to the states to decide.
Only a small percentage of abortions take place after 15 weeks gestation: In 2019, 95.6 percent of abortions reported to the Centers for Disease Control and Prevention occurred before the 16th week.
Most of these rare procedures are performed for younger women and those with unplanned pregnancies, low incomes or limited access to care. But older women who have planned their pregnancies may be more likely to pursue an abortion after 15 weeks because of the higher risk of fetal abnormalities.
Amniocentesis, a procedure in which amniotic fluid is removed from the uterus and tested for chromosomal abnormalities in the fetus, and the all-important mid-pregnancy ultrasound that detects structural anomalies, can only be carried out after 15 weeks and at 20 weeks of gestation, respectively.
Moreover, conditions that can make for a risky pregnancy, like hypertension, asthma, obesity, diabetes and cardiovascular disease, are more prevalent among older women and pose more problems as pregnancies progress, straining the heart, lungs and kidney, several doctors noted.
Women with college degrees have children an average of seven years later than those without degrees, and the average age of first marriage has risen to 28, up from 24 in 1990.
“A lot of women, including myself, delayed childbearing to get through at least part of their career trajectory,” said Dr. Melissa Simon, vice chair for research in the obstetrics and gynecology department at Northwestern University Feinberg School of Medicine in Chicago.
“It puts you in your mid- to late 30s, and you’re considered high-risk in the maternal care world,” she added. “You are at higher risk for genetic anomalies and at higher risk for more complications.”
At least 13 states have banned abortion altogether, and Georgia has banned the procedure at six weeks’ pregnancy. But among states where abortion is legal, Florida is the only one with a 15-week cutoff. (Utah has an 18-week cutoff, while others allow later terminations.)
Mr. Graham’s rationale for setting 15 weeks as the national cutoff is embedded in his legislation’s title, “Protecting Pain-Capable Unborn Children From Late-Term Abortions Act.” The measure contends that after 15 weeks, a fetus feels pain.
But medical experts say the experience of pain requires the brain’s cortex, which doesn’t develop until the end of the second trimester or the beginning of the third trimester — somewhere between 24 weeks and 28 weeks.
Asked about the scientific basis for the assertion, a spokesman for Mr. Graham’s office directed a reporter to the website of the Charlotte Lozier Institute, the research institute of Susan B. Anthony Pro-Life America, which seeks to end all abortions.
The entry regarding pain relies primarily on a paper published in a journal of medical ethics, which does not dispute the developmental timeline for the fetal cortex, but suggests that other brain structures developing earlier may be sufficient for an experience that resembles pain.
But in an interview, the author of that paper, Stuart Derbyshire, an associate professor at the National University of Singapore, said he did not know why Mr. Graham’s bill picked 15 weeks as a cutoff. The American College of Obstetricians and Gynecologists, which represents some 60,000 providers, called the gestational age cited in the law arbitrary and unscientific.
Many scientists say pain-sensing ability depends on consciousness, which, Dr. Derbyshire emphasized, the fetus does not have.
“We were very clear in this paper that we were not saying the fetus in the womb is going, ‘Oooh no, that really hurts, damn this is a bad day,’” Dr. Derbyshire said. “The fetus doesn’t have the self-conscious, reflective experience you and I have.”
The proposed bill also requires that if an abortion takes place after 15 weeks, the fetus should be hospitalized and a physician trained in neonatal resuscitation should be present to provide care. But the earliest viability outside the womb is 22 weeks, according to a study published this year, and experts says that fetuses born before then cannot survive.
While technological advances have made it possible to screen for chromosomal abnormalities earlier in pregnancy than in the past, obtaining a definitive diagnosis depends on prenatal testing: either chorionic villus sampling, which involves taking a sample of tissue from the placenta to test for chromosomal abnormalities, or amniocentesis.
The sampling method can be done earlier than amniocentesis, but it cannot be done safely until after 10 weeks of pregnancy, and the result is often not known till the 12th or 14th week. It is also not readily available at all medical centers, according to Dr. Stephen Chasen, a maternal and fetal medicine specialist at Weill Cornell Medicine.
Many centers rely on amniocentesis, which is not offered before the 15th week of pregnancy because the risks of complications are too high.
Ultrasound scans to check for structural fetal anomalies — which are not the same as chromosomal abnormalities — are done as early as around 10 weeks to 12 weeks of pregnancy, but the comprehensive head-to-toe anatomy scan is done at 20 weeks.
“There are many structural abnormalities, including some really severe conditions involving the brain, heart, kidneys and skeletal structure that can’t be suspected until late in the second trimester or even the third trimester,” Dr. Chasen said.
“The majority of structural abnormalities would not be diagnosed or suspected before 15 weeks,” he added. “A 15-week ban would preclude women with those pregnancies from the opportunity to consider an abortion.”