Preterm birth rates in a large tertiary Australian maternity centre during COVID-19 mitigation measures

Objectives To compare the prevalence of live preterm birth rates during COVID-19 restriction measures with infants born during the same weeks in 2013-2019 in Queensland, Australia. Design, setting, participants Deidentified obstetric and neonatal data were extracted from the Mater Mothers’ electronic healthcare records database. This is a supra-regional tertiary perinatal centre. Main outcome measures Logistic regressions were used to examine preterm birth rates during the beginning of COVID-19 restrictions (16 March-17 April; “early”; 6,955 births) and during the strictest part of COVID-19 restrictions (30 March-1 May; “late”; 6,953 births), according to gestational age subgroups and birth onset (planned or spontaneous). We adjusted for multiple covariates, including maternal age, body mass index, ethnicity, parity, socioeconomic status, maternal asthma, diabetes mellitus and/or hypertensive disorder. Stillbirth rates were also examined (16 March-1 May). Results A reduction in planned moderate/late preterm births was observed primarily during the early restriction period compared with the same calendar weeks in the previous seven years (29 versus an average of 64 per 1,000 births; adjusted odds ratio [aOR] 0.39, 95% CI 0.22-0.71). There was no effect on extremely or very preterm infants, spontaneous preterm births, or stillbirth rates. Rolling averages from January to June revealed a two-week non-significant spike in spontaneous preterm births from late-April to early-May, 2020. Conclusions Planned births for moderate/late preterm infants more than halved during early COVID-19 mitigation measures. Together with evidence from other nations, the COVID-19 pandemic provides a unique opportunity to identify causal and preventative factors for preterm birth.