New research indicates that depression during pregnancy is more common than postpartum depression. The findings appear in this week's British Medical Journal.

Jonathan Evans of the University of Bristol and colleagues analyzed the mood swings of more than 9,000 pregnant women who recorded their states of mind both during and after pregnancy. The team measured all reported symptoms of depression against a recognized depression scale. They found that, contrary to the commonly held belief that pregnancy protects against depression, depression scores actually peaked during pregnancy, at around 32 weeks. Because the severity of the symptoms did not differ before and after childbirth, the authors note, prenatal depression is probably no more likely after childbirth than it is during pregnancy.

Though its consequences are not well understood, antenatal depression may negatively affect the fetus. Indeed, depressed mood during pregnancy has been associated with low birth weight and pre-term delivery, among other things. Thus, the authors note, recognizing and treating depression during pregnancy may be important not only for the mother but for the future well-being of the child.