Post-natal OCD is more common than previously thought, a new study suggests. Experts at Northwestern University in the US estimate that about 11 percent of women who have recently given birth experience symptoms of obsessive compulsive disorder. The incidence rate is almost the same as that for post-natal depression, which affects around one in 10 new mothers. Scientists suspect the conditions may be influenced by the same factors. Symptoms are generally focused on the baby and include fears about accidental injury and dirt or germs. In about half the cases, OCD behaviour improved after about six months. However, some women only begin to display symptoms this long after delivery and the risk remains for up to a year after giving birth. "It may be certain kinds of obsessions or compulsions are adaptive and appropriate for a new parent, for example those about cleanliness and hygiene," said Dr Dana Gossett, from Northwestern University in Illinois. "But when it interferes with normal day-to-day functioning and appropriate care for the baby and parent, it becomes maladaptive and pathologic," she added. OCD is a mental condition characterised by obsessive and frightening thoughts, and an urge to dispel them. This can result in repetitive actions, such as constantly washing hands, or mental rituals that include counting or avoiding "unlucky" colours. The researchers recruited 461 mothers-to-be in hospital and screened them for anxiety, depression and OCD. Tests were carried out two weeks after giving birth and six months after the women had gone home. The results, published in The Journal of Reproductive Medicine, showed an OCD rate of 11 per cent – around five times the risk for the general population.