Mid-pregnancy vitamin D levels and postpartum depression

Postpartum depression (PPD) is a common disorder that affects 10-15% of postpartum women, and it can have negative effects on both the mother and newborn. Recent studies have suggested that low levels of vitamin D are associated with poor mood and depression. The aim of this prospective study was to evaluate a possible association between PPD and serum levels of 25-hydroxy vitamin D3 (25(OH)D3), a reliable measurement of vitamin D, during mid-pregnancy.

The source population consisted of all pregnant women between 24 and 28 gestational weeks from June 2012 to October 2012 at Bornova Health Research and Application Hospital, Sifa University. In order to better evaluate a possible effect between vitamin D levels and PPD, individuals with characteristics that put them at risk for developing PPD were excluded from the study. Serum 25(OH)D3 levels were evaluated mid-pregnancy in the study group. Serum 25(OH)D3 concentrations ≤20ng/mL (50nmol/L) were classified as a mild deficiency and those ≤10ng/mL (25nmol/L) were classified as a severe deficiency. Pregnant subjects having complications during birth or with the newborn after delivery were excluded from the study. The Edinburgh Postnatal Depression Scale (EPDS) was used to assess maternal PPD 1 week, 6 weeks, and 6 months after delivery. A Pearson correlation was used to measure the strength of the associations between the EPDS scores and vitamin D levels analyzed during the three time periods. A logistic regression analysis was used to determine the independent effects of vitamin D on PPD.

Six hundred and eighty-seven pregnant women were included in this study. After excluding women due to PPD risk factors (in two stages), 179 pregnant women were screened for vitamin D levels during mid-pregnancy and in the 6th month postpartum. Eleven percent of our study group had severe vitamin D deficiency and 40.3% had mild vitamin D deficiency. The frequency of PPD was 21.6% at the 1st week, 23.2% at 6th week, and 23.7% at the 6th month. There was a significant relationship between low 25(OH)D3 levels in mid-pregnancy and high EPDS scores, which is indicative of PPD for all three follow-up periods (p=0.003, p=0.004 and p<0.001, respectively). In addition, there was a significant negative correlation between vitamin D levels and EDPS at all three time points (r=-0.2, -0.2, -0.3, respectively).

Vitamin D deficiency in mid-pregnancy may be a factor affecting the development of PPD. More extensive studies are required to be carried out on this subject.