A small observational study of nine women from Wuhan, who had pneumonia caused by coronavirus COVID-19 in their third trimester of pregnancy, revealed no evidence of severe adverse outcomes. There were two cases of neonatal distress, two cases of premature membrane rupture and four preterm labours (>36 weeks), but all resulted in live births. COVID-19 symptoms in pregnant women were similar to those reported in non-pregnant adults.
The authors pointed out that studying pregnancy outcomes is vital, as pregnant women can be particularly susceptible to respiratory pathogens and severe pneumonia due to being immunocompromised, and also due to pregnancy-related physiological changes, potentially leaving them at higher risk of poor outcomes.
They say the lack of evidence for intrauterine transmission is similar to that seen with severe acute respiratory syndrome (SARS), although SARS has a high incidence of adverse maternal and neonatal complications.
The effect of mothers being infected during the first or second trimester of pregnancy remains unclear. These results were in small numbers, late in pregnancy, and each neonate was born by caesarean section.
The authors say longer-term follow-up will be necessary. Future research should determine whether COVID-19 could damage the placenta as this could increase the risk of vertical transmission, they add.