As the name postpartum depression indicates, this is a type of depression identified by appearing at a particular time of life. And there are a variety of causes that could bring about an episode of depression at this particular time. For one thing, a person who has suffered from depression in other circumstances does not become immune to the same factors causing depression after a child is born. In addition, as at any other time, a stressful or painful event - either involving the baby and delivery or having to do with family, friends, pets, employment, housing, or any other important aspect of life - may lead to depression at this time. And a woman who has been strongly reactive to hormonal changes, as in premenstrual syndrome (PMS), may also react strongly to her body’s attempts to adjust to her post-pregnancy life.

Risk factors specifically related to the situation of being a new parent, such as feeling overwhelmed, having insufficient sleep, or not having enough support can trigger postpartum depression. Specific risk factors linked directly to the pregnancy include elevated risk if the pregnancy was unwanted, if it was difficult, and if the newborn has any type of medical problem or issue, including temporary issues such as colic.