Is first trimester vitamin D status in nulliparous women associated with pregnancy related hypertensive disorders?

Objectivesthis study aimed to explore if maternal vitamin D status in early pregnancy was associated with pre-eclampsia and pregnancy-induced hypertension. Relationships between vitamin D status and blood pressure at the start of pregnancy as well as the occurrence of a mid-pregnancy drop in blood pressure were also explored. This secondary analysis was completed to investigate a possible mechanism for the association between vitamin D status and pregnancy related hypertensive disorders.Design and settingdata were obtained from the Amsterdam Born Children and their Development study, a prospective community-based cohort study based in Amsterdam, The Netherlands.Participantsa total of 2074 nulliparous women without pre-existing hypertension and with a known vitamin D status before 17 weeks gestation were included in the study. Vitamin D status was categorized into four groups: “normal” (≥50 nmol/L), “insufficient” (30–49.9 nmol/L) “deficient” (20–29.9 nmol/L) or “severely deficient” (<20 nmol/L).Measurementslogistic regression analysis was used to investigate if vitamin D status was related to the odds of experiencing pre-eclampsia or pregnancy-induced hypertension. Models were corrected for maternal age, ethnicity, pre-pregnancy BMI, smoking and socioeconomic status. χ² and ANOVA tests were used to investigate relationships between vitamin D status and the blood pressure parameters.Findingswhen compared to women with a normal vitamin D status, women who were severely deficient had an increased risk for pre-eclampsia (OR 2.08; 95% CI, 1.05–4.13), but the association was rendered non-significant after correction (OR 1.88; 95% CI 0.79–4.48). There were no associations between vitamin D status and pregnancy-induced hypertension, starting blood pressure or the occurrence of a mid-pregnancy drop in blood pressure.Key conclusionsno strong evidence was found for an association between first trimester vitamin D status and pregnancy related hypertensive disorders in nulliparous women.Implications for practiceat this time, vitamin D supplementation is not warranted for the specific purpose of preventing pregnancy related hypertensive disorders.