New coronavirus leaves pregnant women with wrenching choices—but little data to guide them

Science ’s COVID-19 reporting is supported by the Pulitzer Center.

Do newborn babies need to be separated from mothers infected with the new coronavirus? A growing number of families and doctors are facing this difficult question. The scant data available have led to apparently contradictory recommendations: Some health authorities, including in China and the United States, recommend isolation of newborns from their infected mothers; others, including the World Health Organization (WHO), strongly recommend breastfeeding and keeping mothers and babies together, while taking precautions such as the mother wearing a mask.

More than 200 million pregnant women around the world are potentially at risk of infection with the new virus. Studies are only beginning to shed light on the degree of danger that pathogen, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), represents to them and their newborns. The initial data seem cautiously reassuring, but researchers around the world are racing to collect data that should provide more definitive answers.

For now, however, “It’s a philosophical question: What do you do when you don’t have data?” says Manuel Schmid, a neonatal expert at the University Hospital Zurich. He and his colleagues have opted for a middle ground, given the known benefits of physical contact and breastfeeding, which boosts a newborn’s immune system. “We advise parents and talk with them about risks and benefits,” he says. The decision is ultimately in the family’s hands, and it depends on factors including the health of the mother and baby. “It seems most children are not affected [by the new virus], and those who are affected seem to have mild disease.”

This dilemma is only one of several that pregnant women face during the pandemic. Many hospitals, in an effort to prevent the spread of the virus to staff or other patients, have reportedly prohibited all visitors, even including a pregnant woman’s partner.

The glimmer of good news is that the disease the virus causes, coronavirus disease 2019 (COVID-19), rarely causes severe complications in children, including newborns, based on the limited data so far. Among 731 children in China with confirmed COVID-19 and significant symptoms, only 21 developed severe or critical disease, researchers reported in Pediatrics this month. Other studies have shown that babies can be infected with the virus without getting sick.

One new study followed 33 babies born to infected mothers in Wuhan, China. Only three tested positive for the virus in the days after birth. They all developed signs of pneumonia, but the two who were born full-term recovered within a few days and appeared to have cleared the virus by the time they were 6 days old, researchers reported in JAMA Pediatrics yesterday.

The third, born more than 2 months early, spent 11 days in the neonatal intensive care unit with several complications, including respiratory distress and a bacterial infection. However, such problems are common in infants born so prematurely, the authors note, so the virus may not have caused the baby’s symptoms. The baby also tested negative for the virus 7 days after birth and eventually made a full recovery.

The three infected babies were born by cesarean section and separated from their mothers at birth, so it isn’t clear how they got the virus. Researchers have so far failed to find it in umbilical cord blood, vaginal swabs, and amniotic fluid. Most data suggest babies do not get infected with the virus before birth, but two studies published yesterday in JAMA suggest it might be possible.

The clue came from a specific kind of antibody, called IgM, which is the first type that forms after an infection. Some kinds of antibodies, called IgG, are known to pass from the mother to the fetus through the placenta, protecting babies from bacteria and viruses they might encounter after birth. All seven of the babies tested in the studies had IgG antibodies to the new coronavirus, presumably from their mothers. IgM antibodies, however, are usually too large to cross the placenta. Nevertheless, researchers found IgM antibodies to the new coronavirus in three of the seven babies.

Their presence in the babies’ blood suggests the infants might have been exposed to the virus in utero and developed their own antibodies. However, the authors of an accompanying commentary note that tests for IgM antibodies can frequently give incorrect results. “More definitive evidence is needed,” they say, before pregnant women and their doctors assume that babies can be infected in utero.

Chinese medical guidelines on the new coronavirus recommend newborns be isolated from infected mothers for at least 2 weeks or until the mother is no longer considered infectious. They also recommend against infected mothers breastfeeding. The U.S. Centers for Disease Control and Prevention (CDC) also takes a cautious stance, recommending that “facilities should consider temporarily separating the mother who has COVID-19 … from her baby until the mother’s transmission-based precautions are discontinued.” However, CDC adds that “risks and benefits of temporary separation of the mother from her baby should be discussed with the mother by the health care team.”

Yet as the preliminary reassuring data have emerged, says David Baud, an expert on emerging infectious diseases and pregnancy at the Lausanne University Hospital, he and his colleagues have shifted from recommending isolation and no breastfeeding to WHO’s more nuanced approach.

Provided a mother is well enough, “We do not separate mothers and babies,” he says. “And we really encourage breastfeeding,” while recommending that a mother wears a mask, washes her hands and breasts before feeding, and takes other precautions to avoid spreading the virus to her baby. If a mother is too sick to breastfeed, she should be given the chance to pump her milk if she wishes, he says.

Breastmilk is known to help protect babies against infections in several ways, including by transferring antibodies against infections a mother has fought off, notes Pura Rayco-Solon, a WHO scientist who helped develop the guidelines. No one has reported testing for antibodies against COVID-19 in breastmilk, but one study in 2004 found antibodies to the SARS virus, which is related to SARS-CoV-2, in the breastmilk of a mother who had recovered from a COVID-19–like disease during pregnancy and later gave birth to a healthy, full-term infant. So far, no evidence has been found of the virus itself in breastmilk samples from more than a dozen women infected with COVID-19.

Data on whether pregnant women have more severe cases of COVID-19 or less are unclear. Reports from China involving more than a dozen women infected with COVID-19 late in pregnancy suggest their symptoms, if any, are similar to those of other adults. But Denise Jamieson, an expert on emerging infectious diseases and pregnancy at Emory University, says it is too soon to understand the full impact of the disease during pregnancy. “I’ve stopped saying the data we have are reassuring,” she says. “We don’t have nearly enough information to draw conclusions.”

The outbreaks of SARS and Middle East respiratory syndrome, two other diseases caused by coronaviruses, were small enough that few data were collected on pregnant women, but some were worrying. Those with SARS were more likely to require mechanical ventilation and had a higher death rate than nonpregnant patients. Both viruses were associated with higher rates of miscarriage and preterm birth. And because pregnancy alters the immune system, pregnant women are frequently at higher risk for multiple infectious diseases.

To help add evidence, Baud and his colleagues have launched an international registry called COVI-Preg to collect clinical data on those infected and pregnant. (Researchers in San Francisco have launched a parallel registry for the United States.) More than 70 centers worldwide have already joined the international effort, Baud says. “This worldwide surveillance might give us very precious information that we can collect—and implement—very quickly.”