OBJECTIVE: We aimed to determine whether coronavirus-disease-2019 (COVID-19) pandemic exposure duration was associated with PTB and if the pandemic modified racial disparities.

STUDY DESIGN: We analyzed Philadelphia births and replicated in New Haven. Compared to matched months in two prior years, we analyzed overall PTB, specific PTB phenotypes, and stillbirth.

RESULTS: Overall, PTB was similar between periods with the following exceptions. Compared to pre-pandemic, early pregnancy (<14 weeks') pandemic exposure was associated with lower risk of PTB < 28 weeks' (aRR 0.60 [0.30-1.10]) and later exposure with higher risk (aRR 1.77 [0.78-3.97]) (interaction p = 0.04). PTB < 32 weeks' among White patients decreased during the pandemic, resulting in non-significant widening of the Black-White disparity from aRR 2.51 (95%CI: 1.53-4.16) to aRR 4.07 (95%CI: 1.56-12.01) (interaction P = 0.41). No findings replicated in New Haven.

CONCLUSION: We detected no overall pandemic effects on PTB, but potential indirect benefits for some patients which could widen disparities remains possible.