Novel coronavirus infection in the third trimester of pregnancy: perinatal and maternal outcomes

Objective: To investigate the characteristic features of the course of pregnancy, labor, and perinatal outcomes in women who had novel coronavirus disease 2019 (COVID-19) in the third trimester of pregnancy and gave birth after COVID-19.

Materials and methods: The study group included 313 patients divided into subgroups 1 (n=90), 2 (n=154), and 3 (n=69) who had COVID-19 at 28–32, 32.1–36.6 and ≥37 weeks of gestation, respectively. The comparison group included 216 women who gave birth before the COVID-19 pandemic (2019). Histological examination of the placenta was performed in the study (n=87) and comparison (n=20) groups.

Results: COVID-19 at 28–32 weeks increases the risk of fetal growth restriction (relative risk (RR)=5.6; 95% CI 2.4; 13.0; p<0.001), preterm birth (RR=2.7; 95% CI 1.2; 5.8; p=0.01), placental abruption (RR=5.2; 95% CI 1.6; 16.4; p=0.002), fetal distress (RR=4.9; 95% CI 1.7; 13.6; p=0.001), and emergency caesarean section (RR=4.0; 95% CI 1.8; 9.1; p=0.001). The newborns had significantly smaller chest circumferences and lower Apgar scores. The placentas showed marked signs of maternal and fetal vascular malperfusion. COVID-19 at 32.1–36.6 weeks gestation increased the risk of uteroplacental circulation disorders (UPCD) (RR=4.3; 95% CI 1.1; 16.1; p=0.02), preterm birth (RR=2.8; 95% CI 1.4; 5.6; p<0.001), fetal distress (RR=3.9; 95% CI 1.5; 10.3; p=0.003), and emergency caesarean section (RR=3.4; 95% CI 1.6; 7.3, p=0.001). Newborns had a significantly smaller chest circumference and lower Apgar scores. COVID-19 after 37 weeks increased the risk of UPCD (RR=8.0; 95% CI 2.0; 31.9, p=0.001). Vascular abnormalities were most pronounced in the placentas of patients in group 1.

Conclusion: COVID-19 in the early and middle third trimesters is associated with the most adverse perinatal outcomes.