Introduction
Depression is expected to be the leading cause of disability worldwide by 2030 (1). The prevalence is increasing, women being particular at high risk during hormonal transition phases such as pregnancy and the postpartum period (2,3). Systematic reviews report an 12% prevalence of depression antenatally (4) and 19% in the first three months postpartum (5). Antenatal depression is associated with preterm birth, a lower likelihood of initiating breastfeeding, and postpartum depression (6). Both antenatal and postpartum depression are associated with compromised mother-infant bonding, and with adverse effects on later childhood development i.e. attention- and hyperactivity problems (7–9). A previous history of mental illness, in particular depression and anxiety are strongly associated with antenatal (10) and postpartum depression (11).
This public health challenge have led to national and international guidelines recommending a coordinated care plan for pregnant women with a current or a history of mental health disorders (12,13), including psycho-social support and, in more severe cases, antidepressant medication (13,14). Outside pregnancy exercise has shown a positive effect among clinically depressed men and women (15), and interestingly, pregnant women with clinical depression expressed interest in exercise as part of their care (16). In a systematic review from 2014, the authors found that exercise might be effective in treating antenatal depression (17). This was based on six randomised controlled trials (RCTs) with small samples sizes (n=24–92) where adherence to physical intervention was not reported in four studies. Further, it was unclear if treatment allocation was concealed properly and intention-to-treat analysis was not conducted in any of the studies (17). We found that the effect of exercise on self-reported psychological well-being among pregnant women with or at high risk of depression needed to be further investigated and undertook a large randomised controlled trial.