Associations of pregnancy timing relative to the COVID-19 pandemic, maternal SARS-CoV-2 infection, and adverse perinatal outcomes.

Purpose: To examine associations between pregnancy timing relative to the COVID-19 pandemic, maternal SARS-CoV-2 infection, and perinatal outcomes.

Methods: We conducted a retrospective cohort study of 189,097 singleton births in South Carolina (2018-2021). Pregnancy timing relative to the pandemic was classified as pre-pandemic (delivered before March 1, 2020), partial pandemic overlap (conceived before and delivered during the pandemic), or pandemic (conceived and delivered during the pandemic). We examined COVID-19 testing, severity, and timing. Modified Poisson regression models with robust variance were used.

Results: Compared to the pre-pandemic group, the partial overlap group had lower risks of low birthweight (LBW) (aRR=0.93, 95 % CI 0.89-0.97) and preterm birth (PTB) (aRR=0.91, 95 % CI 0.88-0.95). The pandemic group had increased risks of LBW (aRR=1.10, 95 % CI 1.06-1.14), PTB (aRR=1.10, 95 % CI 1.07-1.14), and NICU admissions (aRR=1.13, 95 % CI 1.09-1.17) but a decreased risk of breastfeeding initiation (aRR=0.98, 95 % CI 0.97-0.98). Moderate-to-severe COVID-19 symptoms increased PTB (aRR=1.34, 95 % CI 1.13-1.58). Third-trimester COVID-19 infection increased LBW (aRR=1.23, 95 % CI 1.10-1.37), PTB (aRR=1.18, 95 % CI 1.07-1.30), and NICU admissions (aRR=1.17, 95 % CI 1.05-1.30).

Conclusions: Our findings highlight the importance of considering both maternal COVID-19 infection and pandemic-related factors in optimizing perinatal outcomes.