According to ABC News, the mother of the woman killed by police Thursday after trying to ram her car through White House barricades said her daughter suffered from postpartum depression after the birth of her baby last year.

Authorities have not confirmed that Miriam Carey suffered from the condition, which affects 10 to 20 percent of new mothers in the United States each year.

This type of depression usually develops within weeks of delivery, according to Postpartum Support International, a support network for new mothers. It lasts longer than the temporary “baby blues” that often affect women after delivery, and it can range in severity from mood swings, crying spells and difficulty bonding with one’s baby to a more extreme form known as postpartum psychosis, which can cause delusions, paranoia, and attempts to harm oneself or one’s baby.

“A lot of moms have intrusive thoughts . . . about hurting their baby, choking their baby,” said Lynne McIntyre, PSI’s mid-Atlantic coordinator, adding that usually women will not act on such thoughts. But with postpartum psychosis, “these mothers have gotten to a point where they can’t distinguish reality from delusions,” she said.

Postpartum depression is caused by a number of factors, including dramatic hormone changes after delivery and increased tension from caring for a newborn. Left untreated, it can lead to chronic depression and affect mother-child bonding. Treatment can include support groups, changes in diet and sleep patterns, and medication.

Postpartum psychosis is much more rare, affecting 1 to 2 women per 1,000 childbirths. The risk of postpartum depression and postpartum psychosis is higher in women with bipolar disorder or a previous history of postpartum psychosis. There is a 5 percent infanticide or suicide rate associated with the illness.

McIntyre said friends and family members who suspect a woman may be suffering from postpartum depression should encourage her to seek treatment.

“If you recognize that this woman’s personality has changed from pre-baby to post-baby, reach out and talk to her about it,” she said. “The boss who goes to her employee and says, ‘You’re not yourself, go home, call your doctor’ — that person is doing the right thing.”