Seasonality of depressive symptoms during pregnancy

Various risk factors have been identified for antepartum depression. This study evaluated seasonal influences on antepartum depressive symptoms. Data of 2,438 pregnant women on current depressive symptoms was obtained from a large-scale cross-sectional study in The Netherlands. Most women were screened during the first trimester. Depressive symptoms were assessed using the Edinburgh Postnatal Depression Scale (EPDS) and dichotomized using ≥ 9 as cut-off score. The seasonal relationship between antepartum depressive symptoms and the month of assessment was estimated by fitting a sinusoidal curve to the data. A total of 323 women (13.2%) scored above cut-off. In the full sample, we found no significant evidence for seasonal influences on depressive symptoms after adjusting for confounders. Additionally, we found that the seasonal influence was obscured by the modification of the effect by current treatment status. In women untreated for psychiatric complaints, we found a minimum of depressive symptomatology in September and a maximum in March. In women treated for psychiatric complaints we found a minimum of depressive symptomatology in December and a maximum in June. Thus, the effects of seasonality are apparent, but opposite in treated and untreated women. However, health professionals should be aware of depressive symptoms the whole year through.