Congenital infection of SARS-CoV-2 in live-born neonates: a population-based descriptive study.

Objective: To evaluate the evidence of mother-to-child transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Methods: This is a descriptive, multicentre, observational study in nine tertiary care hospitals throughout Spain. The study population was women with coronavirus disease 2019 during pregnancy. Mother-to-child transmission was defined as positive real-time RT-PCR of SARS-CoV-2 in amniotic fluid, cord blood, placenta or neonatal nasopharyngeal swabs taken immediately after birth.

Results: We included 43 women with singleton pregnancies and one with a twin pregnancy, as a result we obtained 45 samples of placenta, amniotic fluid and umbilical cord blood. The median gestational age at diagnosis was 34.7 weeks (range 14-41.3 weeks). The median interval between positive RT-PCR and delivery was 21.5 days (range 0-141 days). Fourteen women (31.8%, 95% CI 18.6%-47.6%) were positive at the time of delivery. There was one singleton pregnancy with SARS-CoV-2 RT-PCR positive in the placenta, amniotic fluid and umbilical cord blood (2.2%, 95% CI 0.1%-11.8%). Nasopharyngeal aspiration was performed on 38 neonates at birth, all of which were negative (0%, 95% CI 0%-9.3%). In 11 neonates the nasopharyngeal aspiration was repeated at 24-48 hours, and one returned positive (9.1%, 95% CI 0.2%-41.3%).

Conclusions: The presence of SARS-CoV-2 in placenta, amniotic fluid and cord blood shows that mother-to-child transmission is possible but uncommon.