A study published recently in Archives of Womens Mental Health explored the relationship between maternal and cord blood 25-hydroxyvitamin D (25OHD) and maternal depressive symptoms over the perinatal period. Overall, 126 pregnant women were recruited for this longitudinal cohort study. Depressive symptoms (Edinburgh Postnatal Depression Screen, EPDS) and vitamin D status (25OHD) were measured at three time points in the perinatal period: time 1 (T1; N = 125) EPDS and 25OHD were collected in early pregnancy; time 2 (T2; N = 96) EPDS was conducted in the third trimester with blood collected at time of delivery; and time 3 (T3; N = 88) postpartum. There was a significant inverse relationship between vitamin D status and depressive symptoms at all time points in this sample. This association remained after controlling for confounders. Low cord blood 25OHD levels were inversely associated with higher EPDS scores in the third trimester. Thus study thus underscores the need to consider screening women diagnosed with vitamin D deficiency for depression and vice versa. Vitamin D may represent an important biomarker for pregnant and postpartum women diagnosed with depression.