[Epidemiology and characteristics of SARS-CoV-2 infection in the newborn and pregnant woman. Transplacemental transfer of immunoglobulins].

Introduction: SARS-CoV-2 infection during pregnancy and its impact on the newborn were, in the first months of the pandemic, unknown. Recent studies have provided information on the clinical involvement in the newborn and its evolution.This work shows how passive immunity varies in the newborn in relation to the moment of maternal SARS-CoV-2 infection during pregnancy.

Population and method: Observational, prospective and longitudinal study in a third level hospital. Epidemiological and clinical data from mothers and their newborns were collected from May 2020 to June 2021.

Results: A total of 109 mothers and 109 neonates have been included. 28.4% of maternal infections were in the first trimester, 24.8% during the second and 58.8% in the third. 56% of maternal infections were symptomatic and only one pregnant woman with severe respiratory infection was admitted to intensive care. The mean gestational age of the newborns was 39 weeks, with a mean weight of 3232 g and a head circumference of 35 cm. Eight newborns born from mothers with SARS-CoV-2 required admission to the neonatal ICU: 2 due to jaundice, 2 due to respiratory distress, 1 due to moderate prematurity, and 3 due to other causes unrelated to infection attributable to SARS-CoV-2. IgG-type antibodies were positive in 56.9% of newborns. Of the mothers infected during the 1 st trimester, IgG were positive in 32.2% of the newborns, in the second trimester 81.5% were positive and in the third 58.8%. No neonate had positive IgM.

Conclusions: SARS-CoV-2 infection during pregnancy provides IgG antibodies to half of newborns. The presence of antibodies in the newborn is more likely when the infection has occurred in the second trimester of pregnancy.