Temporal trends in pregnancy outcomes during a health system shock: A retrospective longitudinal study

To better understand reported COVID-19 pandemic effects on pregnancy, we examined temporal trends in pregnancy outcomes in a diverse population from South London, United Kingdom. We included 31,411 singleton pregnancies with complete registration and birth outcomes across pre-pandemic (May 1/2019–March 22/2020, 24.5%), pandemic lockdowns (March 23/2020–July 17/2021, 32.3%), and pandemic without lockdown epochs (July 18/2021–April 22/2023, 43.2%). Multivariable regression was employed to evaluate outcomes by study epoch, adjusting for potential confounders (e.g., ethnicity, deprivation, site), followed by generalized additive modelling to visualise monthly trends. Of 17 outcomes: six had stable trends (e.g., preterm birth, stillbirth); eight showed linear trends, either decreasing (e.g., gestational age at birth, vaginal tears) or increasing (e.g., Caesareans, postpartum haemorrhage); and three showed quadratic (complex) trends (e.g., secondary mental health services, labour induction). Overall, most outcomes during the pandemic mirrored pre-pandemic trends, with observed fluctuations likely due to site-specific responses.