Background

Serological data on mothers with COVID-19 infection during pregnancy and delivery and on their babies are scarce. Neonatal SARS CoV2 infection has been reported to be low.

The aim of our study was to describe serological response in mothers with COVID-19 infection and in their children at delivery and in the next 6 months. We also aimed to investigate the effect of maternal antibodies on neonatal infection.

Methods

Multicentre prospective study from March-October 2020. Mothers diagnosed with COVID-19 during pregnancy or delivery from the Spanish national cohort GESNEO were included. Serologic test was anti-nucleocapsid IgG.

Participants were divided into three groups according to SARS-CoV-2 tests at delivery: acute infection (positive PCR, negative IgG), recent infection (positive PCR, positive IgG), past infection (negative PCR, positive IgG/ confirmed infection during pregnancy).

Results

141 women(mean age 33 years; Interquartile range 29-36) were included. 48(34%) with acute infection, 43(30.5%) with recent infection and 50(35.5%) with past infection.

Positive IgG in mothers and children are shown in figure 1.

IgG in cord blood was more likely to be positive in children if their mothers had been symptomatic(75.8%vs51.1%;p=0.03) or had been admitted to the hospital due to COVID-19 infection(90%vs.57.6%;p=0.08).

Four children had a positive SARS-CoV-2 PCR in the first 15 days of live. All neonatal infections were in children born to mothers with acute infection(8.3%vs.0;p=0.01).

Conclusions

Transplacental passage of maternal antibodies was very high in mothers with recent or past infection at delivery. These antibodies were lost during the first months of life in infants, and were uncommon at 6 months of age.

Neonatal SARS-CoV-2 infection was exceptional, as in previous reports. Maternal antibodies may have a protective effect in transmission of SARS-CoV-2 to newborns.