An OB-GYN reviews the early research and the protective role of the placenta.

Giving birth in a pandemic considerably ups the stakes of concern. Pregnant women around the world are worried they will catch Covid-19 and pass it on to their newborn baby. And we know that viral infections in pregnancy and postpartum can lead to poor outcomes in babies.

Much remains unknown about the coronavirus’s effects on pregnant women and babies, but a recent prepublished manuscript titled “Infant Outcomes Following Maternal Infection With SARS-CoV-2” demonstrates highly encouraging results.

The new data shows that babies born to women with Covid-19 demonstrate no increase in low birth weight, difficulty breathing, apnea, or respiratory infections through the first eight weeks of life.

Based on what scientists know right now, there is no evidence indicating pregnant women are more at risk of contracting Covid-19 than the general public, public, but they are at a higher risk of getting sick from the virus.

During pregnancy, women have a temporarily suppressed immune system and physiologic changes in their lung function. These changes put pregnant women at a higher risk of respiratory problems when they contract similar viruses, such as influenza or pneumonia. OB-GYNs therefore consider pregnant women to be an at-risk group for respiratory compromise if they contract Covid-19. Additionally, preterm labor is a known risk when pregnant women contract viral illnesses such as MERS, SARS, and influenza. Preterm labor most likely results from the severity of the maternal illness and is not directly linked to the virus itself. In other words, preterm labor is not simply a result of contracting these viruses but rather dependent on the degree of illness that results.

In addition to preterm labor, OB-GYNs are concerned about a pregnant woman’s potential to pass Covid-19 to her baby during gestation. This is an example of what doctors call vertical transmission. Fortunately, data surveillance so far indicates that in utero coronavirus infections are very rare. According to the American College of Obstetricians and Gynecologists July practice advisory, “the data are reassuring that vertical transmission appears to be uncommon.”

The new data shows that babies born to women with Covid-19 demonstrate no increase in low birth weight, difficulty breathing, apnea, or respiratory infections through the first eight weeks of life.

NIH research indicates that in utero mom-to-baby transmission is rare because the placenta is missing key components the virus needs to enter the fetal circulation, namely ACE2 receptors and the TMPRSS2 enzyme. Both the ACE2 receptor and TMPRSS2 are present in the placenta but only in tiny amounts. The low levels likely explain why SARS-CoV-2 is unlikely to cross the placenta from mom to baby.

Over the past few months, scientists have studied more than 1,500 cases of maternal coronavirus infections. Current management guidelines for infants born to mothers with SARS-CoV-2 are based on data from the National Registry for Surveillance and Epidemiology of Perinatal Covid-19 Infection.

Current guidelines are based on data from previous experience with maternal respiratory infections, such as SARS and MERS, combined with incoming studies on Covid-19. The PRIORITY study (Pregnancy Coronavirus Outcomes Registry), a collaborative project between researchers at UCSF and UCLA, is an ongoing effort to track outcomes of pregnant women who contract SARS-CoV-2. This data surveillance adds valuable additional infant-outcome data beyond the neonatal period to better inform management policies and guidelines.

The PRIORITY study’s first publication brings some encouraging and reassuring news to the medical community. Data indicates that infants born to Covid-19-positive mothers do well in the first six to eight weeks after birth.

The manuscript, accepted for publication in Clinical Infectious Diseases, reports the infant outcomes of 179 pregnancies complicated by Covid-19 infection compared to a control group of 84 Covid-19-negative gestations.

The PRIORITY study data showed no increase in preterm birth, NICU admission, or upper-respiratory infections. The study cohort yielded no pneumonia or lower-respiratory infection cases through the first eight weeks of life.

The babies born to mothers with Covid-19 also showed a very low rate of acquiring the infection. Only 1.1% of infants tested positive in the first six to eight weeks when born to a mother who had Covid-19, confirmed by a positive SARS-CoV-2 PCR test. The Covid-19-positive infants demonstrated minimal symptoms.

The study authors note the limitations of the paper and encourage further studies to confirm newborn incidence rates, as they “were unable to estimate the incidence of infant SARS-CoV-2 infection because infant testing was incomplete and might be biased by both false-positive and false-negative results.”

The PRIORITY study’s control group includes both symptomatic and asymptomatic women who tested positive for SARS-CoV-2. The researchers indicate this cohort may not be representative of all U.S. pregnancies. The authors also note an underrepresentation of Black and LatinX moms in the study cohort compared to the current CDC statistics of pregnant women infected with SARS-CoV-2.

To improve future study participation, PRIORITY launched a Reproductive Health Equity and Birth Justice Core to increase enrollment of underrepresented groups.

Finally, the authors note that infant admissions to the NICU were higher among infants born to Covid-19-positive moms, and the babies were born at an earlier gestational age. The study authors were unable to determine if the increase in NICU admissions was directly related to SARS-CoV-2 or if the hospital practices for the management of mothers testing positive for Covid-19 explain the difference.

Thank you to Elemental for publishing this article on Medium.

Blog Author: Dr. Jeff Livingston 

Main Blog Photo By: Carolyn Cole/Los Angeles Times/Getty Images