- Pregnant women with COVID-19 were less likely to report symptoms of fever
- Pregnant women with COVID-19 infection more likely to require intensive care
- The mother has to compromise her own immune defense in order to preserve the baby’s health
Will COVID-19 hit me harder because I’m pregnant? If I’m infected, will the virus damage my baby? Data on pregnancy and COVID-19 are woefully incomplete. But, study has recently shown that pregnancy does appear to make women’s bodies more vulnerable to severe COVID-19, the disease caused by SARS-CoV-2. That’s partly because of pregnant women’s uniquely adjusted immune systems, and partly because the coronavirus’ points of attack—the lungs and the cardiovascular system—are already stressed in pregnancy.
The analysis, which encompassed 77 studies conducted globally and was published in the British Medical Journal, looked at 11,432 pregnant women admitted to hospital and diagnosed as having suspected or confirmed COVID-19.
The study said, compared with non-pregnant women of reproductive age, pregnant and recently pregnant women with COVID-19 were less likely to report symptoms of fever. The prescription for caregivers is simple: Protect pregnant patients. The first ones who need the masks are pregnant women. The first to avoid social contact should be pregnant women.
About four out of every 100 pregnant women with COVID-19 appear to require intensive care. The best data available so far were published by the Centers for Disease Control and Prevention (CDC) late in June. Among 91,412 women of reproductive age with coronavirus infections, the 8207 who were pregnant were 50% more likely to end up in intensive care units (ICUs) than their non-pregnant peers. Pregnant women were also 70% more likely to need ventilators, although they were no more likely to die. CDC’s data only offer a partial view, however. Pregnancy status was only available for 28% of the 326,000 US women of reproductive age whose coronavirus infections had been reported to CDC by early June.
A second paper, published by the Public Health Agency of Sweden last month in Acta Obstetricia et Gynecologica Scandinavica, used a more complete data set. Using data for all of Sweden during 4 weeks in March and April, researchers calculated infected pregnant women’s rate of ICU admission compared with that of infected non-pregnant women of reproductive age. The study was small: Only 13 coronavirus-infected pregnant women and 40 non-pregnant infected women were admitted to Swedish ICUs in that time frame. But, Baud says, “From my point of view, it is the most robust data.”
The results were sobering: The researchers found that pregnant or immediately postpartum women with COVID-19 were nearly six times as likely to land in ICUs as their non-pregnant, COVID-19–infected peers.
It’s well known that pregnancy boosts the risk of serious disease from respiratory viral infections. During the H1N1 flu epidemic of 2009, pregnant women accounted for 5% of US deaths, although they constituted about 1% of the population. One study found pregnant women with severe acute respiratory syndrome (SARS), which is caused by a virus that’s a close cousin of SARS-CoV-2, were significantly more likely to be admitted to the ICU and to die than non-pregnant peers.
Viral infections can be more severe in pregnant women in part because “the entire immune system is geared toward making sure not to create any antifetal immune response,” says Akiko Iwasaki, an immunologist at the Yale School of Medicine. “The mother has to compromise her own immune defense in order to preserve the baby’s health.”
At the same time, the immune system is far from inactive in pregnancy, and “the really significant immune response to the infection certainly has the potential to cause complications,” says Carolyn Coyne, a virologist at the University of Pittsburgh.
Pregnant women’s blood has an increased tendency to clot, thought to be due to their need to quickly staunch bleeding after delivering a baby. But the coronavirus itself can have a similar effect.
Elevated dangers to the mother don’t end with delivery. The study followed all 675 pregnant women admitted for delivery at three New York hospitals during 4 weeks in late March and April. After giving birth, nine of 70 infected women, or about 13%, had at least one of three complications that doctors watch for after delivery: fever, low blood oxygen, and hospital readmission. Among 605 non-infected women, 27, or 4.5%, had one of these problems.
Experts all say better data are desperately needed to understand and address the risks to pregnant, coronavirus-infected women. Jamieson notes that registries gathering data on pregnant women infected with H1N1 influenza in 2009 and with Zika in 2015 and 2016 were abandoned after those epidemics passed.