Infant mortality in the U.S. has increased by 7% since the 2022 Dobbs v. Jackson U.S. Supreme Court decision overturned the constitutional right to abortion, according to an October 2024 study.

Those findings followed another study that reported a 12.7% rise in infant mortality in Texas after the implementation of Senate Bill 8, which bans abortions after a fetal heartbeat is detected. Except for medical emergencies, the law effectively makes abortions illegal in the state after about five to six weeks’ gestation.

Both studies noted larger increases in deaths among infants born with birth defects. This suggests women are delivering more babies with severe congenital malformations who have no hope of survival beyond a few hours, days or, at most, a few weeks.

But even before this new research substantiated such a link, clinicians who specialize in care for high-risk pregnancies warned about the potential consequences of the new abortion laws.

We are researchers focused on maternal and child health who evaluate the safety of medications during pregnancy. We identify medications that might raise the risk for birth defects or pregnancy loss.

We also evaluate the effectiveness of policies and initiatives aimed at improving pregnancy outcomes, including whether stricter abortion laws could result in more infant deaths.

Birth defects: A leading cause of infant mortality

Birth defects affect 3% of pregnancies in the U.S.

They can be caused by exposures to certain medications, infections, maternal diseases or genetics. For many, causes are unknown.

While birth defects can develop at any time during pregnancy, most occur during the first three months of pregnancy, a critical time for organ development. More than 5% of pregnancies are exposed to about 200 medications with the potential to cause birth defects.

Many birth defects are treatable; orofacial clefts and some heart defects, for example, can be corrected with surgery. Some cause lifelong disability and some are fatal, resulting in babies who are stillborn or die shortly after birth. Birth defects are a leading cause of infant mortality, accounting for about 20% of deaths in the first year of life.

Among anomalies considered lethal, not all result in pregnancy loss or immediate death at delivery. For example, more than half of infants with trisomy 18, a chromosomal abnormality that causes severe heart defects or breathing problems, die within the first week of life. Only 13% survive until their first birthday.

Anencephaly, a birth defect that affects the development of the skull and brain, results in either stillbirth or death within the first weeks of life. But there is one case report of an infant who survived to her second birthday.

More than 80% of women will choose to terminate a pregnancy with anencephaly when detected before 24 weeks’ gestation, according to data from before the Dobbs decision. Given the profound effects on parents’ lives, this choice is very personal. But in many states, these women may no longer have a choice. Because of abortion laws with limited or no exceptions, women who carry a fetus with a fatal condition have no legal option other than to carry their pregnancy to term.

Legal landscape of abortion laws

As of January 2025, 16 states have total abortion bans in effect or restrictions that do not permit abortions after six weeks. In nine of these states, lethal birth defects are not considered an exception.

But even in states with those exceptions, the legal wording used to craft the legislation is often confusing to health care providers. Statutory language does not always use medical terms and may assume a certainty about pregnancy outcomes that does not exist. For example, even anencephaly does not meet the commonly used statutory definition of “no viability outside the uterus.”

Such uncertainty adds to hesitation – and fear – on the part of doctors and nurses who may face steep penalties, including criminal charges and prison time, should they provide an abortion that is later deemed illegal in a court of law.

Prenatal care too late

In 2023, prenatal care began after the first trimester for about 24% of pregnancies in the U.S.

In our February 2024 study of a national sample of nearly 640,000 privately insured pregnant women, the median time to prenatal care was eight weeks. In other words, for more than half of women living in a state with a six-week abortion ban, obstetric assessments would likely commence too late to consider an abortion if a birth defect were detected.

More than 6,000 women in our study were exposed to medications that can cause birth defects within the first six weeks of pregnancy. These include medications used to treat common yeast or urinary tract infections, drugs used for migraine or weight loss, and blood pressure medications, to name a few. Nearly all of those women – 96% – had no prenatal care prior to taking the medication, and many may not have been aware they were pregnant. For more than 80% of these pregnancies, prenatal care started after six weeks, too late to prevent exposure to unsafe medications or to screen for potential birth defects and to consider pregnancy termination in states with stricter abortion bans.

Importantly, prenatal identification methods of birth defects range from screening maternal blood for chromosome abnormalities, which is done at 10 weeks’ gestation, to a second-trimester ultrasound to look for fetal structural defects, to procedures such as chorionic villus sampling or amniocentesis to evaluate for genetic conditions. These are all performed after six weeks of pregnancy.

Even if screening might still fall within abortion cutoffs, the probability to detect adverse outcomes in utero varies substantially.

For example, valproic acid is a medication that treats epilepsy, migraine and some mental health disorders. About 1% to 2% of women taking valproic acid become pregnant each year. Valproic acid causes birth defects that can be detected in utero such as oral clefts or spina bifida. But it also increases the risk for autism and adverse cognitive defects, which may be diagnosed years after delivery.

Currently, there is no law addressing instances when an adverse outcome is probable but cannot be confirmed before delivery. Hence, stricter abortion laws are expected to not only increase inevitable infant deaths but also births of infants with severe disability.

Almut Winterstein receives funding from NIH, FDA, CDC, AHRQ, The Bill and Melinda Gates Foundation, the state of Florida, and Merck, Sharp and Dohme. She has received consulting honoraria from Novo Nordisk, Bayer, Syneos, Ipsen and Lykos. She has chaired the FDA Drug Safety and Risk Management Advisory Committee and now serves as consultant for similar FDA committees.

Dr. Rasmussen receives funding from NIH, FDA, and CDC. She also serves on scientific advisory committees for several pregnancy registries, including registries for Harmony Biosciences, Axsome Pharmaceuticals, Biohaven Pharmaceuticals (recently acquired by Pfizer), Myovant Sciences, and Novo Nordisk.