Depression is as common in women during pregnancy as it is after giving birth, but signs of depression like tiredness, trouble sleeping, emotional changes, and weight gain may also occur normally during pregnancy.

Studies that define perinatal depression as occurring during pregnancy and up to 12 months after childbirth, suggest that up to 1 in 20 women in this group are suffering from major (severe) depression, with as many as 13% of women having major or minor depression.

Major depression is defined as lasting 2 weeks or longer and accompanied by five or more symptoms that substantially impair a person's ability to fully carry out normal, everyday activities.

Post partum depression has been studied primarily as a problem for women following childbirth, but earlier detection of this condition can improve women’s quality of care.

Factors contributing to depression during or after pregnancy include personal or family history of depression or substance abuse, anxiety about the unborn child, problems with previous pregnancy or birth, and marital or financial problems. Additional factors contributing to depression after childbirth may include changes in hormone levels, feeling tired and lack of sleep, doubts about being a good parent, and changes in work and home routines.

According to the report, evidence shows that psychotherapy and/or antidepressants can be effective treatments for women with perinatal depression. Currently there are only a small number of high-quality studies to support this treatment claim. The report suggests that women who are pregnant or breastfeeding talk with their doctors about the advantages and risks of taking antidepressants.

The evidence review also looked at the advantages of screening pregnant women for depressive symptoms. Available evidence suggests that screening can identify perinatal depression but is more accurate at identifying major depression. Screening is able to detect depression in pregnant and postpartum women as well as in the general population in primary care settings. Whether used for major or minor depression, tests are relatively accurate in identifying women who do not have depression, but are less precise in identifying those who do.

Available research suggests that providing psychosocial support to pregnant and postpartum women with depression may decrease symptoms.