Editor’s note: This article has been significantly revised since original publication. Please see correction note below.*

One of the first measures that Republicans in the 115th Congress proposed was the “Heartbeat Protection Act.” On January 11, a group led by Steve King of Iowa introduced a bill that would require doctors nationwide to “check for a fetal heartbeat” before performing an abortion, and prohibit them from completing the procedure if they found one. In December, Republicans in the Ohio state legislature put forth a similar measure. Governor John Kasich vetoed it, observing that such a law would almost certainly be struck down as unconstitutional, but approved a 20-week abortion ban.

Opponents of the heartbeat bills have pointed out that they would eliminate abortion rights almost entirely—making the procedure illegal around four weeks after fertilization, before many women realize that they are pregnant. These measures raise even more elementary questions: What is a fetal heartbeat? And why does it matter?

The idea would have been unthinkable before the advent of a technology developed in 1976: real-time ultrasound. At six weeks, the “heartbeat” is not audible; it is visible, a flickering that takes place between 120 and 160 times per minute on a black-and-white playback screen. As cardiac cells develop, they begin to send electrical pulses that cause their neighbors to contract. Scientists can observe the same effect if they culture cells in a petri dish.

Doctors do not even call this rapidly dividing cell mass a “fetus” until nine weeks into pregnancy. Yet, the current debate shows how effectively politicians have used visual technology to redefine what counts as “life.”

Since the mid-1990s, opponents of abortion have deployed ultrasound in their attempts to restrict abortion access. Five states have enacted “informed consent” laws, which require doctors to show their patients ultrasound images, and in some cases to describe the images, before performing an abortion. Two of those laws have been struck down by state courts. Twenty other states require a doctor to at least offer to show a woman seeking an abortion ultrasound.

These measures are based on two assumptions: First, that an ultrasound image has an obvious meaning. Second, that any pregnant woman who sees an ultrasound will recognize this meaning. Science does not bear either assumption out.

* * *

The origins of fetal ultrasound lie in stealth warfare. Ultrasound technology was first developed to scan vast spaces, rather than telescope in on infinitesimal cell masses. In the 1880s, the French scientists Pierre and Jacques Curie discovered that they could produce sound waves with frequencies of millions of cycles per second by applying electricity to quartz crystals. Following the sinking of the Titanic in 1912, several scientists and mathematicians experimented with these “ultrasound” signals to determine the presence of icebergs underwater.

However, the real push came during World War I, when German submarines blockaded the Atlantic. The French, British, and American navies rushed to develop devices that could surveil U-Boats. The first known sinking of a submarine detected by hydrophone took place in the Atlantic in April 1916. During World War II, the Allied forces continued to dump resources into improving sonar capabilities.

After the war, army trained scientists and army funded laboratories demobilized the technology, turning away from the ocean, toward women’s bodies. In the early 1960s, doctors in Europe, Japan, and in the United States simultaneously developed and promoted the widespread use of ultrasound in clinical settings. The First International Conference on Diagnostic Ultrasound took place in Pittsburgh in 1965. That same year, fetal images began to spread across popular culture.

In January, Life magazine published a feature entitled “A Sonar ‘Look’ at an Unborn Baby.” It centered on a photograph of a woman, lying beneath the “water-sac” ultrasound scanning device, and a photograph of the screen showing her reading. The caption tells readers that the black-and-white solar flare appearing on the screen is in fact the fetal skull. “The astonishing medical machine resting on this pregnant woman’s abdomen in a Philadelphia hospital is ‘looking’ at her unborn child in precisely the same way a Navy surface ship homes in on enemy submarines,” the text reads.

On April 30, 1965, Life published another cover story that would become iconic: “The Drama of Life Before Birth” presented a series of dramatic color photographs by the Swedish photojournalist, Lennart Nilsson. Annotations detailed the developmental stages of an embryo from fertilization to 28 weeks. One page showed a fetus enclosed, forehead straining against the amniotic sac; another, showed a fetus suspended in a dark void surrounded by pinpoints of light resembling stars. Nilsson called it “spaceman embryo.” The following year, Nilsson published a book on embryology for expecting couples, A Child Is Born. It quickly became an international bestseller.

These images produced a new and unprecedented vision of human development. Before ultrasound, medical care received by pregnant women had depended on their testimony, or how they described their own sensations. Ultrasound made it possible for the male doctor to evaluate the fetus without female interference. Ultrasound images carried the associations of objectivity typically accorded to the camera, and they conferred authority on the doctor who interpreted their contents. They seemed to give him immediate access to the tiny human floating inside his patient’s body. Of course, ultrasound technology has been a crucial component of prenatal care, too. Imagery obtained through ultrasound can alert doctors to potentially serious problems in a pregnancy—such as placental issues or congenital defects in the fetus.

Later, Nilsson admitted that he staged his photographs using aborted material; this was how he had been able to manipulate the position and lighting of the embryos to such dramatic effect. But the image of the fetus as a tiny “spaceman” remained lodged in the popular consciousness.  Stanley Kubrick helped make it iconic with his film 2001: A Space Odyssey, which concludes with a sequence featuring a “Star Child” floating through space, a direct citation of Nilsson’s photographs.

Critics have offered varying interpretations of the sequence. It is an allegory about how technology will destroy the human race; it is an allegory about how we will be reborn through technology. What was clear, as the Star Child floated in its tiny, incandescent amniotic sac, was the suggestion that he floated in a void. The framing of the ultrasound image was notable for what it excluded: the woman. In order to make the fetus visible, it made her disappear.

* * *

Real-time ultrasound became a standard part of prenatal treatment in the early 1980s. Almost as soon as it did, opponents of abortion enlisted it in their cause. It became an article of faith that women would respond to seeing ultrasound images by “recognizing” that the fetus gestating inside them was a “baby”—and, by extension, that abortion would be murder.

In 1983, the doctors John C. Fletcher and Mark I. Evans published an article in The New England Journal of Medicine on “Maternal Bonding in Early Fetal Ultrasound Examinations.” Fletcher and Evans recounted the stories of several women who decided to forego abortions after having ultrasounds. One, who had been beaten by her partner, and then discovered during her medical examination that she was pregnant, was shown an ultrasound and asked how she felt. She told the researchers, “It certainly makes you think twice about abortion! I feel that it is human. It belongs to me. I couldn’t have an abortion now.” In a second case, an expecting mother decided to carry her pregnancy to term, even though, the fetus was at high risk for a genetic disorder that would cause severe hormonal problems: “I am going all the way with this baby. I believe that it is human.”

The authors concluded that earlier viewing of ultrasound would lead women to “experience a shock of recognition that the fetus belongs to them.” Bernard Nathanson decided that exposure to ultrasound could help the entire American public undergo a similar conversion process. Nathanson was an improbable character: a doctor who had performed, he said, “thousands” of abortions and helped found NARAL (the National Abortion and Reproductive Rights Action League), before becoming before becoming involved in the National Right-to-Life Committee. In 1985, he helped produce and narrated a half-hour documentary that purported to use real time ultrasound to show an abortion as it took place: The Silent Scream.

The inspiration for the film came from a contretemps between Ronald Reagan and the American College of Obstetricians and Gynecologists. In January 1984, President Reagan had publicly stated that the fetus “suffers long and agonizing pain during an abortion,” and the medical organization had issued a statement clarifying that this was impossible: a fetus did not develop the neurological pathways necessary to experience pain until the third trimester. Nathanson signed a counterstatement, and vowed to settle the matter by “photographing” an abortion.

The Silent Scream is framed in a way intended to stress its medical and scientific credibility. (“If anyone ever looked the part of the doctor, it is Bernard N. Nathanson,” one Los Angeles Times piece on the film began.) In the opening shots, a voice-over announces that, “all the material in this film is authentic.” Nathanson speaks as if he speaks for the entire medical profession, saying that ultrasound images “have convinced us”— doctors—“beyond question that the unborn child is simply another human being, another member of the human community indistinguishable from you or me.”

The centerpiece of The Silent Scream is a bizarre scene, in which Nathanson sits in a living room in front of a television on which what appears to be a real time ultrasound image is playing. A model of a fetus lies, face down, on the ottoman at his knee. Ignoring the doll, Nathanson describes what is happening, constantly referring to the fetus on screen as “the child.”

“The child is serene in its sanctuary.”

“The child is now moving in a much more personal manner … it is rearing … the child is extremely agitated and moving in a violent manner … The child’s mouth is open, screaming.”

“This is the child’s mouth open, in the silent scream of a child threatened imminently with extinction.”

Nathanson narrates as if these events are taking place in real time. However, the ultrasound had been edited and sped up to make it appear as if the fetus were moving in response to the medical instruments, even though, as many doctors stressed, there was no evidence that reflexes reflected sentience or susceptibility to pain.

As the ultrasound stills, the soundtrack shifts to funereal organ music. “There was once a living, defenseless, tiny human being here.”

Many doctors decried The Silent Scream. But it was screened repeatedly on national television. After premiering on Jerry Falwell’s televangelism show, it aired five times within its first month on major networks. Throughout the 1980s, abortion opponents continued to use Nathanson’s language and imagery to redefine fetuses as persons as part of a campaign to pass state measures that criminalized abortion. In 1986, the year after The Silent Scream debuted, Minnesota passed a “fetal homicide law”; today 38 states have similar statutes.

In 1991, the feminist writer Susan Bordo would observe that ultrasound images had played a key role in reducing the status of mothers to “fetal incubators.” She quoted the pro-life doctor Michael Harrison.

“The fetus could not be taken seriously as long as he remained a medical recluse in an opaque womb; and it was not until the last half of this century that the prying eye of the ultrasonogram rendered the once opaque womb transparent, stripping the veil of mystery from the dark inner sanctum, and letting the light of scientific observation fall on the shy and secretive fetus…”

* * *

Today, the kinds of photographs that stunned the readers of Life in 1966 have become commonplace. Every rom-com involving an unplanned pregnancy—from Knocked Up and Juno to Bridget Jones’s Baby—seems to include an obligatory scene in which the reluctant mother is shown an ultrasound and decides to keep her child. Celebrity ultrasounds have become their own subgenre of tabloid “baby bump” stories.

In many ways, social media have heightened the social reality of the unborn. Expecting parents post ultrasound photos on Facebook and Instagram; they go to “Keepsake Ultrasound” chains in order to buy DVDs of 3-D and 4-D images; which in turn sustain an entire cottage industry on Etsy. Last year, an American couple posted a video of their sonogram fast-forwarded so that their fetus appeared to be clapping in time as they sang, “When You’re Happy and You Know It Clap Your Hands.” The Internet debated whether or not the video was “a hoax.” That is, they debated whether in fact this fetus understood the lyrics of a song and responded to them on cue. Were they serious? The fantasy clearly appealed: The post was viewed on YouTube nearly 12 million times. Yet it remains unclear what the popular enthusiasm for fetal images actually means.

New “informed consent” laws and the Congressional “heartbeat bill” follow the same logic that The Silent Scream did. Their sponsors act as if ultrasound images “prove” that a fetus is equivalent to a “baby,” and that pregnant women only have to be shown ultrasound images in order to draw the same conclusion. But the “heartbeat” made visible via ultrasound does not actually demonstrate any decisive change of state in the cell mass that might become a fetus.

Diane Horvath Cosper, an OB-GYN who works for Physicians for Reproductive Health in Baltimore and Washington, D.C. points out that, as a benchmark, the heartbeat is “kind of arbitrary.” “Two days before we couldn’t see the activity,” Cosper says, “but the cells were there, and they already had that contractile activity.” What the appearance of the flicker on the ultrasound shows is not a change of state but a threshold of the imaging technology.  

In July 2015, the Centers for Disease Control released a report indicating that women were having abortions at far lower rates than they had in the 1980s and 1990s. Charmaine Yoest, the former president of Americans United for Life, credited ultrasound with the drop. “There’s an entire generation of women who saw a sonogram as their first baby picture,” Yoest told the Associated Press. “There’s an increased awareness of the humanity of the baby before it is born.” But there is no evidence that pregnant women react to ultrasound images in the way that Yoest suggested.

Indeed, the evidence suggests the opposite. Economists have argued that the falling abortion rates—now at their lowest level since 1971—track the falling birth rate in general. Research shows that different women react differently to ultrasound images depending on their attitudes toward their pregnancy. While older mothers, and women who have struggled to conceive often express great joy, women who do not desire a child often remain indifferent. A 2014 study published by the journal Obstetrics and Gynecology, which drew on the medical records of nearly 16,000 women seeking abortions, found that viewing an ultrasound had a negligible impact on whether they decided to proceed.

These findings are not surprising. After all, nearly 60 percent of abortions are obtained by women who already have at least one child; these women know what pregnancy means. For them, “informed consent” laws add insult to inconvenience, slowing down their access to care while belittling their ability to make decisions about their own bodies. But pregnant women aren't the only audience for forced ultrasounds. Like many other uses of this technology across history, The Heartbeat Protection Act enlarge the fetus in the public eye, while edging women out of the picture.  


* This article originally stated that there is "no heart to speak of" in a 6-week-old fetus. In fact, the heart has already begun to form by that point in a pregnancy. The article also originally stated that an expectant mother participating in a study decided to carry her pregnancy to term even after learning that the fetus was suffering from a genetic disorder, when in fact the fetus was only at high risk for a genetic disorder. The article originally stated, as well, that Bernard Nathanson headed the National Right-to-Life Committee and became a born-again Christian. Nathanson was active in, but did not head the committee, and was never a born-again Christian, but rather a Roman Catholic. The article originally stated that many doctors in 1985 claimed fetuses had no reflexive responses to medical instruments at 12 weeks. Finally, the article originally stated that John Kasich vetoed a bill from Indiana's legislature, instead of Ohio's legislature, after which the article was incorrectly amended to state that Mike Pence had vetoed the bill. We regret the errors.