Study design and population
This prospective, observational study involved epidemiological information from pregnant women with SARS-CoV-2 between March 1st and May 31st, 2020. Data were collected from the Spanish Registry of COVID-19.15 A total of 100 Spanish centers participate in the Registry, representing 49.95% (n = 172,000) of total deliveries (N = 359,770) carried out in 2019 in Spain.16 Finally a total of 70 centers included cases in the present study. The study was firstly approved by the Puerta de Hierro University Hospital Ethics Committee, and subsequently by the Ethics Committee of each participating hospital. Procedures were in concordance with the Declaration of Helsinki. Oral informed consent was obtained from each participant.