Adverse Outcomes for Newborns of Mothers with COVID-19 Associated with Social Vulnerability, Preterm Birth

Infants born to mothers with SARS-CoV-2 infection were at low risk of contracting the virus, with the primary factors associated with adverse health effects being maternal social vulnerability and preterm birth, a new study found.

The study, published in JAMA Network Open, included 255 babies born to women who tested positive for SARS-CoV-2 infection at 11 hospitals in Massachusetts. Of those, 225 (88.2%) were tested for SARS-CoV-2, with 5 (2.2%) testing positive during birth hospitalization (95% CI, 1.0-5.1). One infant tested positive for SARS-CoV-2 after discharge during non-routine clinical visits.

The study found minimal direct health effects from SARS-CoV-2 infection within 30 days of hospital discharge.

“We found low rates of SARS-CoV-2 transmission from mothers who tested positive around the time of delivery to their infants, at 2.2%, and overall favorable short-term neonatal outcomes in Massachusetts,” lead author Asimenia Angelidou, MD, PhD, neonatologist at Boston Children’s College and instructor in pediatrics at Harvard Medical School told Contagion. “This is consistent with data from other large international cohorts (Spain, UK). Neonates were mostly affected by the virus indirectly, for example through preterm birth and its sequelae.”

Maternal social vulnerability, determined by ZIP code using a US Centers of Disease Control and Prevention index of factors such as poverty, unemployment and education, was identified as a risk factor for positive SARS-CoV-2 testing in newborns.

“We expected the mode of delivery or the degree of maternal illness to increase the risk of newborn infection,” Angelidou said. “What surprised our team was that not only was this not the case, but also the most significant risk factor for positive testing in a newborn was being born to a socially-vulnerable mother, which increased their risk 5-fold.”

Those born positive for SARS-CoV-2 had minimal adverse health effects, the study noted. For those whose mothers had worsening COVID-19 symptoms, the risks were greater for preterm birth and associated adverse health outcomes such as the need for resuscitation, CPAP or mechanical ventilation and longer hospital stay.

A social vulnerability index score of 90th percentile or higher was present for 68 mothers (27.2%). Twenty-three mothers (9.2%) had worsening COVID-19 symptoms that prompted delivery. A total of 62 (24.3%) newborns were born with low birth weight or preterm delivery.

“Our results highlight that even during public health emergencies like COVID-19, careful thought is required to avoid unnecessary premature deliveries,” Angelidou said. “​The low rates of neonatal infection and favorable outcomes during the pandemic surge should reassure pediatricians that newborns are unlikely to get acutely ill from the virus in the first month of life. However, newborns can be infected, can have atypical signs of disease and the long-term sequelae of the virus are unknown, so we should remain vigilant, especially with the circulation of new variants. Clinicians and healthcare providers should be mindful of health disparities, which are complex and extend far beyond racial factors.”

The study results were consistent with the PRIORITY study, which evaluated infant outcomes following maternal SARS-CoV-2 infection in the United States.

Studies in Canada and Italy have shown that infants are unlikely to experience severe illness from COVID-19 and that the virus is unlikely to spread from mother to baby.

A recent study found that pregnant mothers with COVID-19 pass antibodies across the placenta to their babies.

“The mechanisms of perinatal viral transmission (from the mother to the fetus) require further investigation,” Angelidou said. “Social vulnerability likely affects health and immunity and our study supports further research in this area. Other next steps include investigations of the long-term effects of the virus on newborns and young children.”