Most people know about postpartum depression, which affects women who've just given birth. But there's not enough research on depression during pregnancy, according to researchers in California.
Depression in a pregnant woman may affect the baby, scientists at Kaiser Permanente say. In a study of more than 700 women, they found that 40 percent of pregnant women reported depressive symptoms, some of them quite severe.
Compared to women who had no symptoms of depression, depressed mothers were twice as likely to deliver prematurely, researchers found. They speculate that could be one reason there have been more premature births in recent years.
The hormonal changes associated with pregnancy are very likely to be part of the reason some women struggle with their moods. But researchers don't discount environmental factors such as poverty, which simply make life more difficult for the woman.