Many of these studies found that a history of previous anxiety or depression is the strongest risk factor for a new onset during the antenatal period. For ex- ample, one study
found that almost half of the women depressed during pregnancy had a past history of major depressive disorder. In addition, another study
found that absence of a previous psychiatric disorder was associated with a greater likelihood of recovery from an- tenatal anxiety and depression after the birth of the child. Nevertheless Raisanen et al. (2014) found that, despite a previous history of depression being the strongest risk factor for a new episode during pregnancy, half of the women depressed during pregnancy had never been depressed before. This suggests that it is not uncommon for the first episode of depression to occur during pregnancy