The report sprang from an unusual collaboration between natural and social scientists at a 2008 conference at the University of Virginia, where participants shared research about pregnancy and parenting. The proceedings were published last year in a book, “Gender and Parenthood: Natural and Social Science Perspectives,” edited by W. Bradford Wilcox, director of the National Marriage Project at UVA, and Kline. They were principal investigators and wrote the "Bodies" report, released today.