Pregnant women who are infected with SARS-CoV-2 are at an increased risk of adverse perinatal outcomes. With this study, we aimed to better understand the relationship between maternal infection and perinatal outcomes, especially preterm births, and the underlying medical and interventionist factors. This was a prospective observational study carried out in 78 centers (Spanish Obstetric Emergency Group) with a cohort of 1347 SARS-CoV-2 PCR-positive pregnant women registered consecutively between 26 February and 5 November 2020, and a concurrent sample of PCR-negative mothers. The patients’ information was collected from their medical records, and the association of SARS-CoV-2 and perinatal outcomes was evaluated by univariable and multivariate analyses. The data from 1347 SARS-CoV-2-positive pregnancies were compared with those from 1607 SARS-CoV-2-negative pregnancies. Differences were observed between both groups in premature rupture of membranes (15.5% vs. 11.1%, p < 0.001); venous thrombotic events (1.5% vs. 0.2%, p < 0.001); and severe pre-eclampsia incidence (40.6 vs. 15.6%, p = 0.001), which could have been overestimated in the infected cohort due to the shared analytical signs between this hypertensive disorder and COVID-19. In addition, more preterm deliveries were observed in infected patients (11.1% vs. 5.8%, p < 0.001) mainly due to an increase in iatrogenic preterm births. The prematurity in SARS-CoV-2-affected pregnancies results from a predisposition to end the pregnancy because of maternal disease (pneumonia and pre-eclampsia, with or without COVID-19 symptoms).

Objective To evaluate the perinatal and maternal outcomes of pregnancies in SARS-CoV-2 infected women, comparing spontaneous and In Vitro Fertilization (IVF) pregnancies (with either own or donor oocytes). Design Multicentre, prospective, observational study. Setting 78 centres participating in the Spanish COVID19 Registry. Patients 1,347 SARS-CoV-2 positive pregnant women registered consecutively between February 26 th and November 5 th , 2020. Interventions Patient´s information was collected from their medical records, and multivariable regression analyses were performed, controlling for maternal age and the clinical presentation of infection. Main outcome measures Obstetrics and neonatal outcomes, pregnancy comorbidities, intensive care unit admission, mechanical ventilation need and medical conditions. Results The IVF group was composed of 74 (5.5%) women whereas the spontaneous group included 1,275 (94.5%) women. Operative delivery rate was high in all patients, especially in the IVF group, where C-section became the most frequent method of delivery (55.4%, compared to 26.1% of spontaneous). The reason for C-section was induction failure in 56.1% of IVF patients. IVF women had more gestational hypertensive disorders [16.2% vs 4.5% among spontaneous, adjusted Odds Ratio (aOR) 5.31, 95% Confidence Interval (CI) 2.45-10.93) irrespective of oocyte origin. The higher rate of ICU admittance observed in the IVF group (8.1% vs 2.4% spontaneous) was attributed to pre-eclampsia (aOR 11.82, 95% CI 5.25-25.87), not to the type of conception, Conclusions High rate of operative delivery has been observed in SARS-CoV-2 infected women, especially in IVF pregnancies; method of conception does not affect foetal or maternal outcomes, except for pre-eclampsia.