Epidemiology of coronavirus disease 2019 in pregnancy: risk factors and associations with adverse maternal and neonatal outcomes

Background: Coronavirus disease 2019 may be associated with adverse maternal and neonatal outcomes in pregnancy, but there are few controlled data to quantify the magnitude of these risks or to characterize the epidemiology and risk factors.

Objective: This study aimed to quantify the associations of coronavirus disease 2019 with adverse maternal and neonatal outcomes in pregnancy and to characterize the epidemiology and risk factors.

Study design: We performed a matched case-control study of pregnant patients with confirmed coronavirus disease 2019 cases who delivered between 16 and 41 weeks' gestation from March 11 to June 11, 2020. Uninfected pregnant women (controls) were matched to coronavirus disease 2019 cases on a 2:1 ratio based on delivery date. Maternal demographic characteristics, coronavirus disease 2019 symptoms, laboratory evaluations, obstetrical and neonatal outcomes, and clinical management were chart abstracted. The primary outcomes included (1) a composite of adverse maternal outcome, defined as preeclampsia, venous thromboembolism, antepartum admission, maternal intensive care unit admission, need for mechanical ventilation, supplemental oxygen, or maternal death, and (2) a composite of adverse neonatal outcome, defined as respiratory distress syndrome, intraventricular hemorrhage, necrotizing enterocolitis, 5-minute Apgar score of <5, persistent category 2 fetal heart rate tracing despite intrauterine resuscitation, or neonatal death. To quantify the associations between exposure to mild and severe or critical coronavirus disease 2019 and adverse maternal and neonatal outcomes, unadjusted and adjusted analyses were performed using conditional logistic regression (to account for matching), with matched-pair odds ratio and 95% confidence interval based on 1000 bias-corrected bootstrap resampling as the effect measure. Associations were adjusted for potential confounders.

Results: A total of 61 confirmed coronavirus disease 2019 cases were enrolled during the study period (mild disease, n=54 [88.5%]; severe disease, n=6 [9.8%]; critical disease, n=1 [1.6%]). The odds of adverse composite maternal outcome were 3.4 times higher among cases than controls (18.0% vs 8.2%; adjusted odds ratio, 3.4; 95% confidence interval, 1.2-13.4). The odds of adverse composite neonatal outcome were 1.7 times higher in the case group than to the control group (18.0% vs 13.9%; adjusted odds ratio, 1.7; 95% confidence interval, 0.8-4.8). Stratified analyses by disease severity indicated that the morbidity associated with coronavirus disease 2019 in pregnancy was largely driven by the severe or critical disease phenotype. Major risk factors for associated morbidity were black and Hispanic race, advanced maternal age, medical comorbidities, and antepartum admissions related to coronavirus disease 2019.

Conclusion: Coronavirus disease 2019 during pregnancy is associated with an increased risk of adverse maternal and neonatal outcomes, an association that is primarily driven by morbidity associated with severe or critical coronavirus disease 2019. Black and Hispanic race, obesity, advanced maternal age, medical comorbidities, and antepartum admissions related to coronavirus disease 2019 are risk factors for associated morbidity.