1. Introduction
The recent outbreak of COVID-19 pneumonia, caused by SARS-CoV-2 virus, has highlighted the role of viral infections during pregnancy as well.1-3 The importance of these diseases will probably increase as we face growing risks of pandemics, which may affect the pregnant mother and the foetus4.
Viral infections during pregnancy raise several clinical challenges including adverse pregnancy outcomes and birth defects in the offspring.5 Previous studies have shown that SARS during pregnancy may result in spontaneous miscarriage, preterm delivery, and intrauterine growth restriction.6
Other maternal viral infections (e.g. cytomegalovirus, hepatitis B, herpes simplex, influenza, rubella, varicella zoster) have also been found to affect foetal development.4,7,8 However, the results of these studies are conflicting.
The Hungarian Case-Control Surveillance of Congenital Abnormalities (HCCSCA) is one of the largest case-control data sets of birth defect surveillance in the world.9 The total number of control new-borns (without any congenital anomaly) in this database is 57,231.
The aim of the present study was to estimate the effect of viral infections on the development of pregnancy complications and on birth outcome, using the data set of the HCCSCA.