Effects of Hurricane Michael on Access to Care for Pregnant Women and Associated Pregnancy Outcomes.

: Disasters are associated with worse perinatal outcomes, perhaps due to inadequate prenatal care (PNC). : Using 2017-2019 Florida vital statistics, we compared PNC use before and after Hurricane Michael. We categorized counties as most affected (Area A) or less affected (Area B and C). We examined whether Michael's effects on perinatal outcomes varied by maternity care availability and used the Baron and Kenny method to assess whether delayed PNC initiation mediated perinatal outcomes. Log-binomial regression and semi-parametric linear regression were used, controlling for maternal and ZIP code tabulation area characteristics. : Compared to the one-year period pre-Michael, the week of the first PNC was later in all areas in the one-year period post-Michael, with the largest change in Area A (adjusted difference 0.112, 95% CI: 0.055-0.169), where women were less likely to receive PNC overall (aRR = 0.994, 95% CI = 0.990-0.998) and more likely to have inadequate PNC (aRR = 1.193, 95% CI = 1.127-1.264). Michael's effects on perinatal outcomes did not vary significantly by maternity care availability within Area A. Delayed PNC initiation appeared to mediate an increased risk in small for gestational age (SGA) births after Michael. : Women in Area A initiated PNC later and had a higher likelihood of inadequate PNC. Delayed PNC initiation may partially explain increased risk of SGA.