To examine low maternal vitamin D status as a potential risk factor for high levels of depressive symptoms in a pregnant population.

In the Amsterdam Born Children and Their Development cohort, maternal serum vitamin D (n = 4236) was measured during early pregnancy (median, 13 weeks) and labeled "deficient" (≤ 29.9 nM), "insufficient" (30-49.9 nM), "sufficient" (50-79.9 nM), and "normal" (≥ 80 nM). Maternal depressive symptoms were measured by the Center for Epidemiological Studies Depression Scale at 16-week gestation. The association of vitamin D status with high levels of depressive symptoms (Center for Epidemiological Studies Depression score ≥ 16) was assessed by multivariate logistic regression (final sample, 4101).

Overall, 23% of women had vitamin D deficiency, and 21% of women had vitamin D insufficiency. Women with high levels of depressive symptoms (28%) had lower vitamin D concentrations than women with low levels of depressive symptoms (p < .001). After adjustment for constitutional factors, life-style and psychosocial covariates, and sociodemographic factors, vitamin D deficiency (odds ratio [OR], 1.48; 95% confidence interval [CI], 1.13-1.95) and insufficiency (OR, 1.44; 95% CI, 1.12-1.85) were significantly associated with high levels of depressive symptoms. Additional analyses revealed a linear trend, with an OR of 1.05 (95% CI, 1.02-1.08) for each 10-nM decrease in vitamin D status.

In this study, low early-pregnancy vitamin D status was associated with elevated depressive symptoms in pregnancy. Further research, using a randomized controlled design, would be required to confirm the causality of this association and the potential benefits of higher vitamin D intake for psychosocial health.