'Post-partum depression is so common we can't really call it an abnormality'

EUGENE, Ore. - The woman killed after a car chase on Capitol Hill on Thursday started showing signs of mental instability last fall after the birth of her child, her boyfriend said.

Miriam Carey's mother credits her daughter's erratic behavior Thursday to postpartum depression.

Medical experts haven't confirmed that yet, but it raises the issue of depression after the birth of a child.

"I am a mother myself. It is the best thing that has ever happened to me," said Dr. Matha Reilly with Oregon Medical Group. "It's also very hard."

Post-partum depression arises from a complex interplay of social and hormonal factors mixed with sleep deprivation.

Mothers may experience a low mood, hoplessness and helplessness following the birth of a child.

"Post-partum depression is so common we cannot really call it an abnormality," Reilly said. "It is part of an adjustment to motherhood."

In Oregon, the weather can be a factor, too.

"Light depression and being cooped up inside," Reilly said. She said she sees more cases of post-partum depression in the late winter and early spring.

And while anywhere from 30 to 60 percent of women can experience it, "we don't really know the cause," Reilly said.