A U.S. researcher says she was surprised by the level of animosity expressed by some divorced women who share custody of their children with their ex-partners. Mindy Markham of the Kansas State University\'s Salina campus initiated the study as part of her dissertation while at the University of Missouri. \"Nearly half of the mothers in this study continue to have conflicted relationships with their ex-partners, and conversations with these women negate the notion that shared physical custody ensures cooperative, less conflicted relationships,\" Markham said in a statement. \"Shared physical custody is not a panacea for post-divorce problems -- and that in some cases it exacerbates them.\" The study involved 20 predominately white, well-educated women ages 26-49 who were divorced or separated from the father of their children. The mothers shared legal and physical custody of the children, who ranged in age from 21 months to age 12 years. Markham identified three patterns of co-parenting -- continuously contentious, always amicable and bad to better. She said eight of the nine women in the continuously contentious relationships didn\'t want to share custody of the children with their ex-partner, but most were told by lawyers or the court they had to. These women said they were concerned about their ex\'s parenting abilities, finances, an ex not paying child support, abuse and the ex unable to separate marital issues from the co-parenting. Seven of the mothers had contentious relationships at the time of separation, but it improved over time, while four mothers had amicable co-parenting relationships, always getting along and trusting their ex as a good parent, Markham said. The findings were published in Family Relations.