Publisher Health

The Texas law banning abortions after about six weeks of pregnancy is based on a singular premise disputed by many medical experts: that once an ultrasound detects electrical cardiac activity in an embryo, its heart is beating and a live birth is on the way.

At this very early stage of a pregnancy, however, the embryo is the size of a pomegranate seed and has only a primitive tube of cardiac cells that emit electric pulses and pump blood.

Language has long been a battleground in the political struggle over abortion, and the sparring now centers on a word with deep resonance: “heartbeat.”

The Texas law, which makes no exceptions for cases of rape or incest, forbids abortion at the time a “heartbeat” can be heard, which usually occurs at six weeks of gestation. The appeal is emotional: Many parents-to-be are moved by sounds during an ultrasound scan. But what the law defines as the sound of a heartbeat is not considered by medical experts to be coming from a developed heart, which forms later in pregnancy.

At least a dozen states have passed similar heartbeat laws that could be established if Roe v. Wade were overturned. At the moment, the Supreme Court appears to be leaning toward upholding a Mississippi law that bans abortion after 15 weeks of pregnancy, effectively ending the right to abortion established by the Roe decision in 1973.

The potentially seismic shifts have brought renewed attention to both the scientific underpinnings of these laws and the medical claims made by educational materials that many states require to be given to women seeking abortions.

Opponents of abortion say that women need to be better informed of its possible consequences, even unlikely ones.

“We really desire for women to be empowered with information,” said Dr. Christina Francis, chair of the American Association of Pro-Life Obstetricians and Gynecologists, which opposes abortion. “Women are intelligent creatures and can make empowered choices when they have all the information they need.”

But many medical societies and experts say the laws and state-mandated educational materials rest on profound misconceptions about embryonic and fetal development and abortion risks. The Texas statute, for example, requires physicians to warn women that they may face a higher risk of breast cancer or infertility if they have an abortion, despite a lack of evidence.

Women are told they could die from an abortion, though the procedure is generally considered safer than a tonsillectomy, and much safer than pregnancy and childbirth. The materials also warn that having an abortion may make women depressed or suicidal, though studies have not found that to be the case.

According to an analysis by the Informed Consent Project at Rutgers University, nearly one-third of statements about abortion made in patient materials from more than two dozen states are medically inaccurate. Most of the inaccuracies pertain to descriptions of the first trimester. They generally misrepresent certain body systems as complete or present at earlier stages of development than they actually are.

“Laws that are written by nonmedical people to regulate the practice of medicine, or dictate what clinicians have to say to their patients, are dangerous and affect our ability to care for patients,” said Dr. Nisha Verma, a fellow at the American College of Obstetricians and Gynecologists, which has objected to the idea that a fetus has a heart at six weeks.

Indeed, the most fraught contention, embedded in the Texas abortion law, is that the fetus at that stage has a heart and that its beating represents a “key medical predictor that an unborn child will reach live birth.”

This sound, discernible on an ultrasound scan, has become a demarcation line in anti-abortion legislation in dozens of states, though most opponents of abortion rights argue that life begins at conception.

While there is little disagreement about the basic developmental biology, there are sharp differences about the significance.

The heart is one of the first organs to start developing, because the embryo’s growth and survival depend on the circulation of blood carrying oxygen and nutrients. The electric activity begins at around six weeks in a tube of cells that will become a heart, after multiple gyrations.

It will bend and loop and twist itself into an S shape. Thick cushions of embryonic tissue will grow toward one another to create walls, and a ridge on the floor of the ventricle will rise to meet them to partition the heart.

If all goes well, four chambers and valves will form by the ninth or 10th week of pregnancy, and the heart will continue developing throughout gestation. But a heartbeat’s familiar “lub-dub, lub-dub” sound is created by the closing of the heart’s valves, which do not exist in the six-week-old cardiac tube.

To opponents of abortion, that is a distinction without a difference. “It is a heart tube, but it is still a heart,” Dr. Francis said. “The shape is different, but that doesn’t change the essence of what it is,” she added.

Dr. Robin Pierucci, a neonatologist who is an associate scholar at the Charlotte Lozier Institute, which opposes abortion, said in an email: “Finding a fetal heartbeat is a sign of health.”

A 2004 study found that when a moving heart tube could be detected at six to eight weeks of pregnancy, a live birth resulted 98 percent of the time, Dr. Pierucci said.

But that study — which compared women who had lost earlier pregnancies with those who had not — also found that cardiac activity did not lead to a live birth among one in five women who had lost previous pregnancies.

The consensus among most medical experts is that the electrical activity picked up on an ultrasound at six weeks is not the sound of a heart beating and does not guarantee a live birth. The sound expectant mothers hear during a scan is created by the machine itself, which translates the waves of electrical activity into something audible.

Doctors are partly to blame for the confusion. Many physicians whose patients are excited about a desired pregnancy will use the word “heartbeat” to describe the cardiac activity heard on an early ultrasound. The word has even crept into the medical literature.

“What you see and hear on an early ultrasound is embryonic activity — electrical currents being sent through cells that will develop at a much later time into a heart,” said Dr. Gabriela Aguilar, an obstetrician-gynecologist and a former fellow with Physicians for Reproductive Health, which supports access to abortion.

In September, representatives of the A.C.O.G., which supports the right to abortion, said in a Senate hearing that “while contemporary ultrasound can detect an electrically induced flickering of a portion of the embryonic tissue at about six weeks gestation, structurally and in function, a fetus’ heart develops over the entire course of pregnancy.”

Heartbeat laws and other state measures intended to discourage abortion often require that women be warned of risks like infertility and cancer. Health providers are required to provide the materials to patients, even if they believe the information exaggerates the risks of abortion or is otherwise misleading.

Texas’ current booklet offers two pages of warnings. Under the heading “Death,” the booklet informs women that the risk of dying of a legal abortion is 0.73 in 100,000, according to the Centers for Disease Control and Prevention.

The section does not say that the risk of dying in childbirth is much greater. There are 17.4 maternal deaths for every 100,000 live births, and rates are still higher among some minority women.

At the same time, the riskiest abortions are late-term, after 20 weeks of gestation. Yet the vast majority of U.S. abortions — more than 90 percent — are performed within the first 13 weeks and pose little risk of death.

Dr. Francis, of the anti-abortion doctors group, said that U.S. statistics were incomplete, since reporting by states was voluntary, and that the risks might be higher.

According to the Texas brochure, “If you give birth to your baby, you are less likely to develop breast cancer in the future.”

The relationship among abortion, pregnancy and breast cancer is complex. Scientists have long known that women who are childless or have their first child after 30 appear to be at higher risk for developing breast cancer, a link that first came to light when high rates of breast cancer were seen among nuns.

But most women who have abortions — 60 percent — have already had at least one child, according to 2019 data from the C.D.C. The current consensus of the National Cancer Institute, the American College of Obstetricians and Gynecologists and the American Cancer Society is that abortions do not increase the risk of breast cancer.

In a section titled “Future Infertility,” women are told that late-term abortions carry a higher risk of death and medical complications “that can cause you to be infertile” and “make it difficult or impossible to become pregnant in the future.”

Infertility experts dismissed the claim. “There may be older data making this association, from when abortions were illegal” and women developed life-threatening infections, said Dr. Marcelle Cedars, president of the American Society for Reproductive Medicine.

But she said she was unaware of any studies establishing a connection. “I would not list infertility as a potential risk of abortion,” she said.

Women “report a range of emotions after an abortion,” including depression or thoughts of suicide, according to Texas’ educational materials.

But one of the largest studies of the experiences of American women who had abortions followed them for five years after the procedure and found that relief was the most common emotion they experienced.

“We found that denying women an abortion had more negative consequences to their mental health than having an abortion,” said M. Antonia Biggs, an associate professor and social psychologist at the University of California, San Francisco, who has tracked the mental health of women who were denied abortions.

Other research shows that women who have had abortions are not at increased risk of depression, post-traumatic stress disorder or suicidal ideation, Dr. Biggs said.

On the other hand, women who were denied abortions experienced higher rates of household poverty, three times the rate of unemployment, a greater likelihood of reliance on public assistance and a higher risk of food, housing and transportation insecurity, Dr. Biggs and her colleagues found.

Christine Mann, chief press officer for the Texas Health and Human Services Commission, declined to respond to questions about the state’s pamphlets.

Staff members are “are reviewing the booklet to ensure it is update to date, in compliance with state law and includes the necessary scientific and factual information so women can make an informed decision on their pregnancies,” she said in an email.