Objective
Approximately 6 to 13% of women suffer from antenatal depression (AD) around the world. AD can lead to several health problems for mother and baby. Vitamin D is a molecule that appears to have great preventive/therapeutic potential against neuropsychiatric disorders. The present study aimed to analyze the association between vitamin D deficiency and AD in pregnant women in a city in the south of Brazil (Pelotas, Rio Grande do Sul). We hypothesize that pregnant women with a positive AD diagnosis have deficient levels of 25-hydroxyvitamin D (25(OH)D).

Methods
This cross-sectional study was conducted within a cohort study (CEP/UCPEL 47807915.4.0000.5339). From this cohort, 180 pregnant women at up to 24 weeks gestation were selected (130 non-depressed and 50 depressed), and depression was diagnosed using the Mini International Neuropsychiatric Interview (MINI-Plus). Blood was collected and stored for later analysis of vitamin D 25(OH)D by the chemiluminescence method. The SPSS program was used for data analysis and results with p < 0.05 were considered statistically significant.

Results
In our study, we showed a significant association between current major depressive episode in the antenatal period and vitamin D deficiency (odds ratio [OR]: 0.9; 95%CI 0.9-1.0, p = 0.003).

Conclusion
Our results demonstrate that vitamin D deficiency may be involved in major depressive disorder in the antenatal period. It is thus advisable to monitor vitamin D levels during the pregnancy-puerperal cycle to minimize mental health problems in women and prevent developmental deficits in children.