The researchers identified symptoms of obsessive-compulsive disorder in 11 percent of women at their second week and sixth month following childbirth, compared to only 2 percent in the rest of the population.
This is the first study of its kind to observe obsessive-compulsive symptoms in mothers after giving birth.
The symptoms are generally only temporary and include such fears as injuring the baby or being exposed to germs. The researchers believe that if the symptoms interfere with their everyday functioning, then it could indicate a psychological disorder.
Dana Gossett, MD, senior author of the study and chief and assistant professor of obstetrics and gynecology at Northwestern University Feinberg School of Medicine, said:
"It may be that certain kinds of obsessions and compulsions are adaptive and appropriate for a new parent, for example those about cleanliness and hygiene. But when it interferes with normal day-to-day functioning and appropriate care for the baby and parent, it becomes maladaptive and pathologic."
The researchers' own upsetting thoughts following birth led them to set out to determine whether the feelings were common among all women.
Emily Miller, MD, and lead author of the study, said: "A compulsion is a response to those obsessive thoughts, a ritualistic behavior that temporary allays the anxiety but can't rationally prevent the obsession from occurring."
OCD can be caused by stress, which may explain why situations such as pregnancy can predispose women to the disorder.
The most common thoughts that were on the minds of women in the study were about dirt or germs, said Miller.
Some even had intrusive thoughts that involved harming their baby.
Miller said: "That can be emotionally painful.You don't intend to harm the baby, but you're fearful that you will."
Gossett mentioned that when she gave birth to her first child she constantly worried about damaging her baby somehow. "It comes into your mind unbidden and it's frightening," she said.
A total of 461 women participated in the study, they were all surveyed at their second week and then 329 were surveyed again at six months - following giving birth. They were recruited during their delivery at Northwestern Memorial. All symptoms were self-reported.
Close to half of the participants said that their OCD symptoms got better by six months. However, new women reported that they experienced symptoms that weren't there during the first two weeks postpartum.
Gossett said: "If those symptoms are developing much later after delivery, they are less likely to be hormonal or adaptive."
Miller said that postpartum OCD represents a distinct postpartum mental illness that isn't that well classified, considering 70 percent of the women who screened positive for obsessive-compulsive symptoms were also found to have symptoms of depression.
"There is some debate as to whether postpartum depression is simply a major depressive episode that happens after birth or its own disease with its own features. Our study supports the idea that it may be its own disease with more of the anxiety and obsessive-compulsive symptoms than would be typical for a major depressive episode."
Written by Joseph Nordqvist