Peripartum onset is defined as starting anytime during pregnancy or within the four weeks following delivery. There is no longer a distinction made between depressive episodes that occur during pregnancy or those that occur after delivery. Nevertheless, the majority of experts continue to diagnose postpartum depression as depression with onset anytime within the first year after delivery.The criteria required for the diagnosis of postpartum depression are the same as those required to make a diagnosis of non-childbirth related major depression or minor depression. The criteria include at least five of the following nine symptoms, within a two-week period:
Feelings of sadness, emptiness, or hopelessness, nearly every day, for most of the day or the observation of a depressed mood made by others
Loss of interest or pleasure in activities
Weight loss or decreased appetite
Changes in sleep patterns
Feelings of restlessness
Loss of energy
Feelings of worthlessness or guilt
Loss of concentration or increased indecisiveness
Recurrent thoughts of death, with or without plans of suicide

Differential diagnosis
Postpartum blues
Postpartum blues, commonly known as "baby blues," is a transient postpartum mood disorder characterized by milder depressive symptoms than postpartum depression. This type of depression can occur in up to 80% of all mothers following delivery. Symptoms typically resolve within two weeks. Symptoms lasting longer than two weeks are a sign of a more serious type of depression. Women who experience "baby blues" may have a higher risk of experiencing a more serious episode of depression later on.
This study found that risk factors such as low education, low income cut off, taking antidepressants, and low social support are all factors that contribute to the higher percentage of these population in developing PPDS. Specifically, indigenous mothers had the most risk factors then immigrant mothers with non-indigenous Canadian women being closer to the overall population. South America
A main issue surrounding PPD is the lack of study and the lack of reported prevalence that is based on studies developed in Western economically developed countries. In countries such as Brazil, Guyana, Costa Rica, Italy, Chile, and South Africa there is actually a prevalence of report, around 60%. In an itemized research analysis put a mean prevalence at 10-15% percent but explicitly stated that cultural factors such as perception of mental health and stigma could possibly be preventing accurate reporting. The analysis for South America shows that PPD occurs at a high rate looking comparatively at Brazil (42%) Chile (4.6-48%) Guyana and Colombia (57%) and Venezuela (22%). In most of these countries PPD is not considered a serious condition for women and therefore there is an absence of support programs for prevention and treatment in health systems. Specifically, in Brazil PPD is identified through the family environment whereas in Chile PPD manifests itself through suicidal ideation and emotional instability. In both cases most women feel regret and refuse to take care of the child showing that this illness is serious for both the mother and child.