Pregnancy and COVID-19: What we do and don’t know about the impact of the coronavirus

Dr. Gretchen LaSalle, a Spokane family doctor who follows COVID-19 trends, is well aware that pregnant women and their babies face more risks and potential adverse effects from the virus.

The women can have more severe symptoms, and other risks might include miscarriages, early births and a low percentage of stillborn births followed in recent studies.

LaSalle agreed with recent findings from a U.S. expert in pediatric infectious diseases who offered another argument for pregnant women to get vaccinated – to minimize detrimental health risks that COVID-19 and newer variants can have on the placenta and fetus.

“What we know is pregnancy is a high-risk time anyway for getting respiratory infections,” LaSalle said. “We see that with flu every year – that pregnant women are at greater risk of various complications from influenza, but similarly with COVID. There are a variety of physiologic reasons for that.”

Dr. Roberta DeBiasi, pediatric infectious diseases division chief at Children’s National Hospital in Washington, D.C, offered her review in an editorial published in the Journal of Infectious Diseases. It covered what is known about possible harmful effects of SARS-CoV-2 infection in pregnant women and babies, on the placenta and what is still unknown.

The virus can trigger inflammatory and vascular responses in the placenta during critical periods of fetal development in symptomatic and asymptomatic cases, based on two studies, the review said.

One study published an analysis of a stillbirth resulting from the delta variant infection during the third trimester, the report said. The other study offered a case series of pregnant women infected with the delta variant associated with stillbirth in two cases and one with severe neonatal illness.

“The authors present a highly plausible mechanism of stillbirth, namely that the virus-induced proinflammatory state ultimately led to placental abruption,” DeBiasi said in a news release.

LaSalle said pregnant women who contract the virus can get very ill.

“COVID can be very harmful for the pregnancy itself; it’s certainly potentially very harmful for the mom,” LaSalle added. “Pregnant women with COVID have higher rates of ICU admission, ventilator support needs and maternal death. There can be higher rates of blood clots that can be life-threatening.”

LaSalle also went over unknowns and knowns on the topic.

Unknown: “What we don’t really know yet are the potential long-term outcomes on the babies themselves regarding COVID infections or the effect on children down the line who were born to infected moms,” LaSalle said. “It doesn’t seem like there’s any at least immediate significant risk as far as fetal malformations.

“But we know that high fever in pregnancy is unhealthy, and fevers themselves can put babies at slightly higher risk of developmental defects. There is a lot we don’t know, which is scary.”

Known: Vaccinations are safe for pregnant women and their babies, LaSalle said. “Even before the vaccines were available and before human trials were conducted, scientists do what are called developmental and reproductive toxicity studies. They use animal models to look for all of these concerns. Does the vaccine affect fetal development? Does it affect reproduction? Does it negatively impact pregnancies?”

“They didn’t see any adverse effects in that regard in animal models, and then we have data from the smaller number of women who did get pregnant during the trials and know that those who were vaccinated compared to those unvaccinated had no greater risk of adverse outcomes.”

Among pregnant women who have chosen to receive the vaccine, a percentage of them are enrolled in registries to monitor the mom, the health of the pregnancy and of the baby, she said. “They haven’t seen any increase in adverse outcomes compared to what we would typically expect at baseline, so that would be the rates of miscarriage, preterm delivery, stillbirth that we saw before we had COVID vaccines. So, there is no increased risk from vaccinations with any of those parameters.”

Known: Adverse impacts of COVID-19 in pregnancy include many factors. One, pregnancy is a relatively immune compromised state, LaSalle said, as the body responds to carrying a fetus.

“We also see farther along in pregnancy, and the bigger that belly gets, the more it pushes up on the lungs and the lungs don’t have as good an opportunity to expand fully. If you add a dangerous respiratory virus on top of that like COVID or flu – and the mom can’t clear that virus or her immune system is dampened down – she doesn’t fight it off as well, then she can’t as well expand her lungs to breathe as fully. It’s more of a set up for complications like bronchitis and pneumonia.”

Known: The vessels of the placenta need oxygenation to help oxygenate the baby and keep the placenta healthy and viable. Regarding the potential higher risks for adverse effects from COVID-19 on the placenta, LaSalle said that wouldn’t surprise her.

“If the mom is not oxygenating well and has to be on a ventilator, that can be harmful to the placenta, certainly,” LaSalle said. “We know that pregnancy already is a higher risk time for blood clots to develop, but then adding COVID onto that, we see significant increases in rates of blood clotting that happen. If you have blood clots to the placenta, then there’s not adequate blood flow to support a healthy placenta.”

Previous studies have documented that the placenta may be detrimentally affected by SARS-CoV-2 infection of the mother. However, maternal comorbidities such as hypertension, preeclampsia and gestational diabetes also could contribute to these findings, the DeBiasi review information said.

“Taking the studies together, it’s evident that if a pregnant woman gets COVID-19, they’re at an increased risk of severe infection,” DeBiasi said. “They’re also at increased risk of adverse pregnancy outcomes due to effects on the placenta, which may vary with specific circulating variants.”

“Despite these previous studies, the precise mechanisms of placental injury are still not clear and require further evaluation. Future research should include appropriate controls to better discern nonspecific versus SARS-CoV-2 specific effects and mechanisms of injury.”

The vaccination rate among pregnant women remains low.

As of May 8, 16.3% of pregnant women identified in Centers for Disease Control and Prevention’s Vaccine Safety Datalink had received at least one dose of a COVID-19 vaccine during pregnancy. Vaccination was lowest among Hispanic (11.9%) and non-Hispanic Black women (6%) and women ages 18–24 (5.5%) and highest among non-Hispanic Asian women (24.7%) and women ages 35–49 years (22.7%).