Why infection poses special risks to pregnant women

ScienceThe COVID-19 report is supported by the Pulitzer Center and the Heising-Simons Foundation.

Obstetrician Yalda Afshar is investigating the effects of COVID-19 on pregnancy. Her baby is due in October.

Photo: APARNA SRIDHAR

Yarda Afshhar hears from his patients daily worries. Is COVID-19 slamming me because I am pregnant? If I get a virus, will it damage my baby? Afshire, a high-risk obstetrician at Ronald Reagan University of California (UC), Los Angeles, Medical Center, understands women’s concerns best. Her first child will be delivered in October.

Data on pregnancy and COVID-19 are terribly incomplete. However, they offer some relief: fetal infections in late pregnancy appear to be rare, and experts are cautiously optimistic that coronavirus does not distort early fetal development ( Sidebar, p. 607). However, new data suggests several substances in other concerns of Afshar patients: Pregnancy is more vulnerable to severe COVID-19 in women’s body caused by SARS-CoV-2 Looks like to. This is because the pregnant woman’s own adjusted immune system and the coronavirus’s attack points (lung and cardiovascular system) are already stressed during pregnancy.

David Bo, a specialist in emerging infectious diseases and pregnancy at the University of Lausanne Hospital, said: A pregnant woman needs a mask first. The first way to avoid social contact should be with pregnant women. “

The best US data available to date was published by the Centers for Disease Control and Prevention (CDC) in late June. Of the 91,412 reproductive-age women with coronavirus infection, 8207 who were pregnant were 50% more likely to enter the intensive care unit (ICU) than their nonpregnant sibs. Pregnant women were less likely to die, but were 70% more likely to need a ventilator.

However, the CDC data only provides a partial view. Pregnancy status was only available to 28% of 326,000 American women of reproductive age who had a coronavirus infection reported to the CDC by early June.

Second article published last month by the Swedish Public Health Service Acta Obstetricia et Gynecologica Scandinavica, Used a more complete dataset. Using 4-week Swedish data from March and April, researchers calculated ICU hospitalization rates for infected pregnant women compared with those of infected non-pregnant women of reproductive age. Did. The study was small. Only 13 pregnant women who were infected with the coronavirus and 40 infected women who were not pregnant were admitted to the ICU in Sweden during this period. But Bo says, “From my point of view, this is the most robust data.”

The results were cool: researchers found that pregnant or newborn women with COVID-19 were more likely to land in the ICU nearly six times as often as non-pregnant COVID-19-infected peers Did.

It is well known that pregnancy increases the risk of serious illness due to respiratory viral infections. During the 2009 H1N1 flu epidemic, pregnant women accounted for approximately 1% of the population, but accounted for 5% of deaths in the United States. One study found that pregnant women with Severe Acute Respiratory Syndrome (SARS) caused by the virus, a close relative of SARS-CoV-2, are much more likely to die in hospitalized ICU than their nonpregnant sibs I understand.

Akiko Iwasaki, an immunologist at Yale University School of Medicine, said that the virus infection in pregnant women could be even more serious, “because it aims to prevent the entire immune system from developing an anti-fetal immune response.” There is. “Mothers have to compromise their immune defenses to keep their baby healthy.”

At the same time, the immune system is far from inactive during pregnancy, “a really important immune response to an infection can certainly lead to complications,” says Carolyn Coin, a virologist at the University of Pittsburgh.

In addition, SARS-CoV-2 attacks the lungs and cardiovascular system. These are already tense during pregnancy. “As the uterus grows, there is less and less space for the lungs, so pregnant women often feel short of breath, which affects your lung function,” said Obstetrics at Emory University School of Medicine. Gynecologist Dennis Jamison says.

Pregnant women also need additional oxygen and blood to carry the fetus to supply it. Up to 50% increase by late pregnancy. This may double the stress that COVID-19 exerts on the cardiovascular system (Science, April 24, p. 356). “The heart is already working with two people,” says Baud. “And if you are a virus known to cause vascular changes, inflammation, this will increase your heart’s workload even further.”

Malavika Prabhu, a maternal and fetal medicine specialist at Weill Cornell Medicine, said in the second trimester that “a large amount of blood flows and the metabolism of organs becomes active, so excess water may flow to places where you do not want to go. Rehydrate your lungs.”

Finally, pregnant women’s blood is more likely to clot. It is thought that this is because it is necessary to stop bleeding immediately after giving birth. However, coronavirus itself has a similar effect (Science, June 5, p. 1039). “COVID is thought to increase the chance of coagulation, and pregnancy increases the chance of coagulation,” said Jamieson.

According to a study by Prab and colleagues in a magazine, the increased risk to mothers does not end with childbirth distortion last month. They followed all 675 pregnant women who had been born in three New York hospitals in late March and four weeks in April. After delivery, nine of the 70 infected women, or about 13%, had one or more of three complications that physicians should note after delivery: fever, low blood oxygen, and readmission. Twenty-seven of the 605 uninfected women, or 4.5%, had one of these problems. “Many illnesses are revealed during the postpartum period, and I learned that COVID-19 is one of them,” says Prabhu. She said 79% of pregnant women who tested positive on admission were asymptomatic.

Experts all say that better data are needed to understand and address the risks to pregnant women with coronavirus infections. Jamieson points out that registries collecting data on pregnant women infected with the H1N1 flu in 2009 and Zika in 2015 and 2016 were abandoned after these epidemics passed. “We really need to invest in a long-term, well-funded surveillance system that captures the consequences of pregnancy.”

Together with a colleague from the University of California, San Francisco, Afshar is a Principal Investigator at the Pregnancy Coronavirus Outcomes Registry, which currently collects data from more than 1100 pregnant women in the United States. She hopes to begin answering urgent questions such as the effects on mothers and fetuses of the drugs given to fight COVID-19. How infections affect maternal immune status; and whether and how anticoagulants should be used in pregnant women with COVID-19.

“It was very strange to be able to give advice to women and their families, witness their stress, and give evidence-based recommendations,” says Afshar. “I lose sleep for every woman I care for. To make sure I do the right thing for her. And so do I.”