The diagnosis for postpartum depression is similar to other forms of major depression. However, the difference between PPD and other forms of depression is that those who are suffering from PPD will typically begin having symptoms a month after they have given birth. In addition to this, the condition may also develop during the pregnancy as well. Many of the causes of PPD are not well understood. However, there are a few factors that are believed to cause the disorder. One cause is the prenatal depression that may be experienced during pregnancy. A woman who has a low self esteem is also at a higher risk for developing PPD.