ABSTRACT
Background: Melbourne's 2020 pandemic lockdown was associated with an increase in stillbirths and a reduction in preterm births (PTB) among singleton pregnancies. Twin pregnancies may be particularly susceptible due to higher background risk. We aimed to compare the rates of adverse pregnancy outcomes in twin pregnancies exposed and unexposed to Melbourne's lockdown. Method(s): Multicentre retrospective cohort study of all twin pregnancies > 20 weeks birthing in all 12 public maternity hospitals in Melbourne. Multivariable log-binominal regressions were used to compare outcomes between a pre-pandemic control group ('unexposed') independently with two lockdown-exposed groups: exposure 1 from 22 March 2020 to 21 March 2021 (pre-vaccination era) and exposure 2 from 22 March 2021 to 27 March 2022 (vaccination era). Result(s): We included 2259 pregnancies. There were fewer PTBs < 37 weeks during exposure 1 compared with the pre-pandemic era (63.1% vs. 68.3%;adjusted risk-ratio (aRR) 0.95;95% confidence interval (CI) 0.88-0.98, P = 0.01). This lower rate was most prominent in iatrogenic PTB for suspected fetal compromise (13.4% vs. 20.3%;aRR 0.94 95% CI 0.90-0.99, P = 0.01). There were correspondingly fewer special care nursery admissions during exposure 1 (38.5% vs. 43.5%;aRR 0.91 95% CI 0.87-0.95, P < 0.001), but no changes in stillbirth (1.5% vs. 1.4%;aRR 1.00, 95% CI 0.99-1.01, P = 0.85). Compared with the pre-pandemic period, exposure 2 was associated with a trend to more PTB < 28 weeks and significantly higher neonatal intensive care unit admissions (25.0% vs. 19.6%;aRR 1.06 95% CI 1.03-1.10, P < 0.001). Conclusion(s): Melbourne's first lockdown-exposure period was associated with fewer preterm twin births for suspected fetal compromise, without any increase in stillbirth.
ABSTRACT
Background: We aimed to measure COVID-19 vaccine uptake among women giving birth in Melbourne and to compare perinatal outcomes by vaccination status. Method(s): Routinely-collected data from all 12 public maternity hospitals in Melbourne were extracted on births >=20 weeks' from 01.07.21 to 31.03.22. Sociodemographic characteristics and perinatal outcomes were compared between COVID-19 vaccinated and unvaccinated women. The primary outcomes were stillbirth and preterm birth in singletons >24 weeks. We calculated the adjusted odds ratio of perinatal outcomes among vaccinated versus unvaccinated women using inverse propensity score weighting regression adjustment with multiple covariates;P < 0.05 was considered significant. Result(s): Births from 32 536 women were analysed: 17 365 (53.4%) were vaccinated and 15 171 (47.6%) were unvaccinated. Vaccination status was significantly associated with multiple sociodemographic factors. Vaccinated women had a significantly lower rate of stillbirth compared with unvaccinated women (0.2% vs. 0.8%, aOR 0.18, 95% CI 0.09- 0.37, P < 0.001). Vaccination was associated with a significant reduction in total preterm births <37 weeks (5.1% vs. 9.2%, aOR 0.60, 95% CI 0.51-0.71, P < 0.001), spontaneous preterm birth (2.4% vs. 4.0%, aOR 0.73 95% CI 0.56-0.96, P = 0.02) and iatrogenic preterm birth (2.7% vs. 5.2%, aOR 0.52, 95% CI 0.41-0.65, P < 0.001). There was no significant increase in congenital anomalies or foetal growth restriction among vaccinated women. Conclusion(s): COVID-19 vaccination during pregnancy was associated with a reduction in stillbirth and preterm birth, and not associated with any adverse impacts on foetal growth or development. Vaccine coverage was significantly influenced by known social determinants of health.