COVID-19: More Research Needed on Maternal and Infant Health Outcomes

By Dezimey Kum, SWHR Communications and Policy Intern

Pregnant individuals and newborns have immune systems that are more susceptible to viral infections than the general population. Research across a variety of infectious diseases — including the Zika virus, the H1N1 flu virus, and the SARS, MERS, and COVID-19 coronaviruses — suggests that pregnant women and their babies are at increased risk for disease-related complications.

Preliminary reports indicate pregnant individuals are at higher risk for developing more severe cases of COVID-19. “Women who get infected with COVID in pregnancy have a higher rate of hospitalization compared to non-pregnant individuals, a higher rate of ICU admission, and a higher rate of intubation,” Dr. Jasmine Johnson, a third-year maternal-fetal medicine fellow and clinical instructor at the UNC Department of Obstetrics & Gynecology, said in an interview. “We know that COVID-19 in pregnancy is risky, and it can lead to adverse outcomes for mom and baby when we think about risk of preterm birth and risk of C-section.”

However, research is still in the early stages and the full impact of COVID-19 on pregnant women and newborns is not yet fully known.

Potential for In Utero Infection and Antibody Transmission

According to the Centers for Disease Control and Prevention (CDC), COVID-19 is uncommon in newborns born to mothers diagnosed with COVID-19 while pregnant. Although some newborns have tested positive shortly after birth, it is unclear whether they contracted the virus before, during, or after birth. Further, most studies have reported no respiratory or other illnesses in infants born to mothers with positive SARS-CoV-2 infection.

According to a recent study published in the American Journal of Obstetrics and Gynecology (AJOG), pregnant individuals previously diagnosed with COVID-19 can pass protective antibodies on to their babies in utero. Participants enrolled in the study had COVID-19 antibodies in their blood indicating a prior infection. Study authors found that 78% of the babies born to study participants had detectable antibodies in blood samples obtained from their umbilical cords.

Infants born during the study were screened for COVID-19 at birth, and there was no indication that any of them had an active COVID-19 infection, implying that the antibodies were passed down via the placenta from the mother. Researchers also noted that mothers who had symptomatic infections had higher antibody levels than those who were asymptomatic.

Risk of Adverse Outcomes

Research on COVID-19 and pregnancy is ongoing, and the studies thus far have reported varying outcomes. A recent analysis of studies noted that COVID-19 in pregnancy was associated with preterm delivery and that maternal infection with the virus could possibly damage the placenta, with potentially adverse outcomes for the fetus. A study of deliveries at a hospital in New York also reported more preterm infants born to COVID-19-positive mothers and that preterm cases were more likely to have some adverse outcomes such as NICU admission.

However, a study from the University of California San Francisco (UCSF) suggested that maternal COVID-19 status was not associated with concerns such as low birth weight, difficulty breathing, apnea, or upper or lower respiratory infection through 8 weeks of age. Another review said that, “in the majority of cases, SARS-CoV-2 seems unlikely to infect or adversely impact newborns of infected mothers.”

Experts also point to evidence from previous infectious disease epidemics, including the 1918 flu pandemic and the SARS epidemic in 2002, that suggest COVID-19 could have long-term effects on newborns that were in utero during maternal infection. Direct virus transmission from mother to fetus and serious birth defects were uncommon in previous infectious disease outbreaks, but there were observed increases in preterm delivery and low birth weight during the 2002 SARS and 2009 H1N1 influenza outbreaks. Preterm birth and low birth weight can increase risk for a variety of health complications including infections, breathing problems, and developmental issues, as well as present a significant economic burden — at least $26.2 billion annually in the U.S.

Disparities in Maternal Health

The COVID-19 pandemic has also highlighted and exacerbated existing health disparities for people of color in the U.S., including those who are pregnant. A CDC report found that “Hispanic and non-Hispanic Black pregnant women appear to be disproportionately affected by SARS-CoV-2 infection during pregnancy.” Black women were already experiencing a maternal health crisis in the U.S. before the pandemic, with Black women three times more likely to experience pregnancy-related death than white women. Many factors contribute to these disparities in maternal health, including systemic health and social inequities.

In a survey of pregnant women conducted early in the pandemic, Black pregnant women reported “greater likelihood of having their employment negatively impacted, more concerns about a lasting economic burden, and more worries about their prenatal care, birth experience, and post-natal needs.” More research is needed to better understand how the COVID-19 pandemic may be worsening these existing maternal health disparities.

Maternal Vaccination

Expert groups recommend that pregnant and lactating individuals have access to the COVID-19 vaccine. Unfortunately, no currently authorized COVID-19 vaccines included pregnant people in initial studies, although some companies are now conducting Phase 2 and 3 follow-up trials to assess vaccination safety, tolerability, and immunogenicity pregnant individuals.

In a preprint study on medRxiv, researchers looked at 131 vaccinated women (who received Pfizer or Moderna), 84 pregnant and 31 lactating. They screened for COVID-19 antibodies in their blood, umbilical cord blood, and breastmilk after all vaccine doses, and again two to six weeks later. Researchers discovered that pregnant women had an immune response that was almost as strong as non-pregnant women. Additionally, umbilical cord blood and breastmilk samples contained vaccine-generated antibodies.

More research is needed to determine the safety and efficacy of the COVID-19 vaccines during pregnancy. In the meantime, the CDC has recommended those who are pregnant consult with their health care providers about the risks and benefits of vaccination. “It can be a really big challenge when you are trying to provide complex medical care just because the data isn’t there” on pregnant people, Johnson said. “We can’t provide the reassurance that we would want to.” (If you are pregnant and choose to vaccinate, you can enroll in the CDC’s V-safe COVID-19 Vaccine Pregnancy Registry.)

Many factors play a role in maternal and infant health outcomes, and research is ongoing to get a better picture of how COVID-19 may affect both the short- and long-term health for these populations. Maternal immunization is potentially the best available choice for protecting both pregnant and lactating individuals, as well as their babies. However, pregnant and lactating individuals must be considered in study designs from the beginning to ensure they have access to the information they need to make confident decisions about their health care.

“COVID has highlighted a flaw in this system we’ve been hoping to change for a long time,” Johnson said. “We want pregnant and lactating women to be included in studies when it comes not just to COVID-19 vaccination but medications.”

SWHR’s blog series on maternal and infant health disparities is supported by a grant from AMAG Pharmaceuticals. SWHR maintains editorial control and independence over blog content.