title: Reply.
authors.affiliation: Department of Obstetrics and Gynecology, University of Arizona College of Medicine, Tucson, AZ. Electronic address: cohenw@email.arizona.edu.
authors.forename: Wayne R
authors.initials: WR
authors.lastname: Cohen
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Biology, Harvard Medical School, Boston, MA.
authors.forename: Emanuel A
authors.initials: EA
authors.lastname: Friedman
mesh_terms: D005260:Female; D006801:Humans; D007743:Labor, Obstetric / Q000502:physiology*; D007744:Obstetric Labor Complications; D011247:Pregnancy