A Registry-Based Observational Study on the Maternal and Fetal Outcomes of COVID-19 Patients in Hong Kong

Objective: To report the clinical maternal and fetal outcomes of pregnant women with coronavirus disease 2019 (COVID-19), along with any associated pregnancy complications, in Hong Kong, China, and to assess the impact of COVID-19 vaccination on these outcomes. Methods: This prospective registry-based observational study included pregnant women who were recruited through convenient sampling and had a laboratory-confirmed severe acute respiratory syndrome coronavirus 2 infection with a cycle threshold (Ct) value result available on admission to eight local hospitals in Hong Kong, China. Data on clinical symptoms, laboratory results, medical treatments, delivery timing and mode, and pregnancy complications were extracted from the Hospital Authority's electronic medical record system. Maternal, fetal, and pregnancy outcomes were compared between unvaccinated pregnant women with COVID-19 and those who had received at least one dose of COVID-19 vaccine before diagnosis. Nonparametric continuous variables and categorical variables were analyzed using the Mann-Whitney U test and the Pearson's chi-squared test respectively. A P value less than 0.05 was considered statistically significant. Results: A total of 164 pregnant women were included, of whom 78 (47.56%) were nulliparous. COVID-19 was diagnosed before 28 weeks' gestation in 30 (18.29%), while 134 (81.71%) were diagnosed at or after 28 weeks' gestation. Sixty-two (37.80%) women received at least one dose of COVID-19 vaccine. There were no significant differences between vaccinated and unvaccinated groups in the time interval between COVID-19 diagnosis and delivery, the Ct value, and the gestational age at infection onset or delivery (P > 0.05). The majority of women were symptomatic at diagnosis regardless of vaccination status (55 (88.71%) in vaccinated group vs. 78 (76.47%) in unvaccinated group (P = 0.052). Symptoms did not significantly differ between groups except for cough (62.90% vs. 47.06%, P = 0.049). The overall rate of severe COVID-19 in pregnant women was low. In total, 5 (3.05%) patients experienced severe COVID-19, with vaccinated patients more likely to receive low molecular weight heparin (LMWH) as part of their treatment (62.90% vs. 42.16%, P = 0.010). Ninety-two (56.10%) women had a spontaneous vaginal delivery, 7 (4.27%) had an instrumental delivery, and 44 (26.83%) and 21 (12.80%) underwent emergency and elective cesarean sections respectively. For fetal outcomes, 14 (8.48%) babies were born preterm and four (2.65% of nonpreterm babies, n = 151) had low birthweight. The median birthweight percentile was 52.18th. There were no statistically significant differences in pregnancy complications or fetal outcomes between vaccinated and unvaccinated groups. Conclusion: The overall rate of severe COVID-19 in pregnant women was low. COVID-19 vaccination did not significantly impact maternal outcomes, except for the use of LMWH. Additionally, the study found no significant differences in fetal outcomes and pregnancy complications between vaccinated and unvaccinated individuals.