As of 2001, experts cannot say what causes postpartum depression. Most likely, it is caused by many factors that vary from individual to individual. Mothers commonly experience some degree of depression during the first weeks after birth. Pregnancy and birth are accompanied by sudden hormonal changes that affect emotions. Additionally, the 24-hour responsibility for a newborn infant represents a major psychological and lifestyle adjustment for most mothers, even after the first child. These physical and emotional stresses are usually accompanied by inadequate rest until the baby's routine stabilizes, so fatigue and depression are not unusual.

Experiences vary considerably but usually include several symptoms.

Feelings:

• persistent low mood
• inadequacy, failure, hopelessness, helplessness
• exhaustion, emptiness, sadness, tearfulness
• guilt, shame, worthlessness
• confusion, anxiety, and panic
• fear for the baby and of the baby
• fear of being alone or going out

Behaviors:

• lack of interest or pleasure in usual activities
• insomnia or excessive sleep, nightmares
• not eating or overeating
• decreased energy and motivation
• withdrawal from social contact
• poor self-care
• inability to cope with routine tasks

Thoughts:

• inability to think clearly and make decisions
• lack of concentration and poor memory
• running away from everything
• fear of being rejected by partner
• worry about harm or death to partner or baby
• ideas about suicide

Some symptoms may not indicate a severe problem. However, persistent low mood or loss of interest or pleasure in activities, along with four other symptoms occurring together for a period of at least two weeks, indicate clinical depression, and require adequate treatment.

There are several important risk factors for postpartum depression, including:

• stress
• lack of sleep
• poor nutrition
• lack of support from one's partner, family or friends
• family history of depression
• labor/delivery complications for mother or baby
• premature or postmature delivery
• problems with the baby's health
• separation of mother and baby
• A difficult baby (temperament, feeding, sleeping, settling problems)
• preexisting neurosis or psychosis