title: Rejoinder.
authors.affiliation: Division of Epidemiology, Statistics and Prevention Research Eunice Kennedy Shriver National Institute of Child Health and Human Development National Institutes of Health, Rockville, MD 20852, U.S.A. kims2@mail.nih.gov.
authors.forename: Sungduk
authors.initials: S
authors.lastname: Kim
authors.affiliation: Division of Epidemiology, Statistics and Prevention Research Eunice Kennedy Shriver National Institute of Child Health and Human Development National Institutes of Health, Rockville, MD 20852, U.S.A. sundaramr2@mail.nih.gov.
authors.forename: Rajeshwari
authors.initials: R
authors.lastname: Sundaram
authors.affiliation: Division of Epidemiology, Statistics and Prevention Research Eunice Kennedy Shriver National Institute of Child Health and Human Development National Institutes of Health, Rockville, MD 20852, U.S.A. louisg@mail.nih.gov.
authors.forename: Germaine M
authors.initials: GM
authors.lastname: Buck Louis
authors.affiliation: National Perinatal Epidemiology Unit, University of Oxford, Oxford 327270, U.K. cecilia.pyper@npeu.ox.ac.uk.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Pyper