Maternal folate status and placental vascular malperfusion: Findings from a high-risk US minority birth cohort.

Introduction: Maternal folate deficiency was associated with preeclampsia (PE) and PE was associated with placental maternal vascular malperfusion (MVM). However, no study has examined the association of maternal folate status with placental MVM.

Methods: We examined the association of maternal folate status and placental MVM in the Boston Birth Cohort. Primary exposure variables were maternal self-reported multivitamin supplement (<2, 3-5, >5 times/week) per trimester; and plasma folate levels (nmol/L) after birth. Primary outcome was presence/absence of placental MVM defined by the Amsterdam Placental Workshop Group standard classification. Covariates included demographics, chronic hypertension, clinically diagnosed PE, eclampsia and HELLP syndrome, gestational and pre-gestational diabetes, overweight/obesity, maternal cigarette smoking and alcohol use. Associations between folate and placental MVM were evaluated using multivariate logistic regressions.

Results: Of 3001 mothers in this study, 18.8% of mothers had PE, 37.5% had MVM. Mothers with the lowest self-reported frequency of folate intake had the highest risk of MVM (OR 1.45, 95% CI 1.03-2.05), after adjusting for the covariates. Consistently, among a subset of 939 mothers with plasma folate levels, folate insufficiency was associated with increased risk of MVM (OR 1.65, 95% CI 1.03-2.63), after adjusting for the covariables. As expected, mothers with low folate and placental MVM had highest rates of PE compared to those of high folate and no MVM (p < 0.001).

Discussion: In this high-risk birth cohort, low maternal folate status was associated with increased risk of placental MVM. Further investigation should explore the association between folate status, placental findings and the great obstetrical syndrome.