Susan Hatters Friedman, M.D.
Mood symptoms frequently occur during pregnancy and the postpartum period and may cause morbidity for both mother and baby. The majority—up to 80%—of women experience the self-limited postpartum "baby blues" (1). Depending on the population surveyed, postpartum depression occurs in approximately one in seven women (10%–20%) (1, 2). The more emergent and rarer postpartum psychosis occurs at a rate of 0.1%–0.2% of women in the general population. Women with bipolar disorder have dramatically elevated rates of postpartum psychosis as well as an increased risk of postpartum depression.
Family and twin studies suggest a genetic contribution to postpartum depression and postpartum psychosis. A recent study of postpartum psychosis in bipolar mothers found an association between polymorphisms in genes encoding components of serotonergic pathways (SERT and 5-HT2A, 5-HT2C), further suggesting that genetic factors modulate susceptibility (3). However, postpartum depression and postpartum psychosis are multifactorial, and contributors include biological/hormonal, psychological, and social factors (such as relationship and financial problems) as well as family history and sleep deprivation (1, 2). Moreover, bipolar disorder increases the risk of postpartum psychosis specifically, while history of mood or anxiety disorder increases the risk of postpartum depression.
Because of the genetic components, it is logical to use psychiatric genetics to help us further understand these phenomena. However, this is not the simple Mendelian genetics of sickle cell anemia, and any genetic studies need to be interpreted bearing in mind the complexities of genetic and nongenetic contributory factors…