Maternal COVID-19 infection and placental abnormality

November 17, 2020
Judith M. Orvos, ELS

a BELS-certified medical writer and editor, and an editorial consultant for Contemporary OB/GYN

Findings from a retrospective study by researchers from NYU suggest that women with COVID-19 in pregnancy have an increased risk of placental abnormalities, regardless of whether their infection is symptomatic.

If their data are confirmed in future studies, say the authors, long-term neonatal follow-up may be warranted in such patients.

Published in The American Journal of Obstetrics and Gynecology,1 the report is from a cohort of women admitted for delivery at ≥37 weeks between March 31, 2020 and June 17, 2020. Placental histopathological findings from 77 women with COVID-19 who delivered a singleton at term were compared to a control group of 56 term patients without COVID-19.

On admission, all of the patients had been tested for COVID-19. None of the controls had obstetrics or medical complications. Multivariable logistic regression models were created for variables that were significant in univariable analyses. A subgroup analysis also was performed to compared women with asymptomatic COVID-19 infection to the controls.

Women with COVID-19 were significantly more likely to be younger (29.9 years vs 32.2 years, P = 0.02), Hispanic (55.8% vs 17.6%, P = 0.01), and to deliver vaginally (74% vs 25%, P < 0.0001) compared to controls.

Of the patients studied, 87% were asymptomatic. In the remainder, any symptoms were mild and included fever, cough, upper respiratory complaints, and shortness of breath. No testing for inflammatory markers or coagulation studies were performed because they were not indicated.

Univariable analyses showed that the placentas of the women with COVID-19 were more likely to have evidence of fetal vascular malperfusion (32.5% vs 3.6%, P < 0.0001) and villitis of unknown etiology (20.8% vs 7.1%, P = 0.030). These findings persisted in a subgroup comparison of women with asymptomatic COVID-19 versus controls.

Frequency of fetal vascular malperfusion abnormalities remained significantly higher in the COVID-19 group (odds ratio [OR] = 12.63, 95% confidence interval [CI] 2.40-66.40) in a multivariable model that adjusted for maternal age, race/ethnicity, mode of delivery, pre-eclampsia, fetal growth restriction, and oligohydramnios.

Frequency of villitis of unknown etiology was more than double in the placentas of women with COVID-19 versus the controls, but the difference was not statistically significant in a multivariable model (OR = 2.11, 95% CI 0.50-8.97).

All of the infants born to COVID-19-positive mothers tested negative for SARS-CoV-2 on polymerase chain reaction.

Despite the increased rate of placental abnormalities in the COVID-19-positive mothers, their infants had birthweights, rates of neonatal intensive care unit admission, and APGAR scores similar to that in infants of mothers in the control group.

The authors hypothesized that “this suggests that the placenta may act as a defensive biological ‘filter,’ offering a degree of protection to the neonate, may modify its immune status or may actively produce factors that may protect the fetus in utero.”

They underscored, however, that there may still be “injury” to the placenta, and noted that the possibility of adverse effects in the neonates points to a need for follow-up in these cases for long-term side effects.



  1. Patberg ET, Adams T, Wek PR, et al. COVID-19 infection and placental histology in women delivering at term. Am J Obstet Gynecol. Published: October 19, 2020. doi: