title: Is human fecundity changing? A discussion of research and data gaps precluding us from having an answer.
abstract: Fecundity, the biologic capacity to reproduce, is essential for the health of individuals and is, therefore, fundamental for understanding human health at the population level. Given the absence of a population (bio)marker, fecundity is assessed indirectly by various individual-based (e.g. semen quality, ovulation) or couple-based (e.g. time-to-pregnancy) endpoints. Population monitoring of fecundity is challenging, and often defaults to relying on rates of births (fertility) or adverse outcomes such as genitourinary malformations and reproductive site cancers. In light of reported declines in semen quality and fertility rates in some global regions among other changes, the question as to whether human fecundity is changing needs investigation. We review existing data and novel methodological approaches aimed at answering this question from a transdisciplinary perspective. The existing literature is insufficient for answering this question; we provide an overview of currently available resources and novel methods suitable for delineating temporal patterns in human fecundity in future research.
authors.affiliation: Office of the Director, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 6710B Rockledge Dr. Room 3131A, Bethesda, MD 20829, USA.
authors.forename: Melissa M
authors.initials: MM
authors.lastname: Smarr
authors.affiliation: Office of the Director, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 6710B Rockledge Dr. Room 3131A, Bethesda, MD 20829, USA.
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Sapra
authors.affiliation: Department of Demography, University of California, Berkeley, CA 94720, USA.
authors.forename: Alison
authors.initials: A
authors.lastname: Gemmill
authors.affiliation: Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY 10032, USA.
authors.forename: Linda G
authors.initials: LG
authors.lastname: Kahn
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, MA 02118, USA.
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Wise
authors.affiliation: Department of Obstetrics & Gynecology, The Ohio State University College of Medicine, Columbus, OH 43212, USA.
authors.forename: Courtney D
authors.initials: CD
authors.lastname: Lynch
authors.affiliation: Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY 10032, USA.
authors.forename: Pam
authors.initials: P
authors.lastname: Factor-Litvak
authors.affiliation: Epidemiology Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20829, USA.
authors.forename: Sunni L
authors.initials: SL
authors.lastname: Mumford
authors.affiliation: Department of Growth and Reproduction and EDMaRC, University of Copenhagen, Rigshospitalet, DK-2100 Copenhagen, Denmark.
authors.forename: Niels E
authors.initials: NE
authors.lastname: Skakkebaek
authors.affiliation: Team of Environmental Epidemiology, Inserm, CNRS, University Grenoble Alpes, IAB Joint Research Center, F-38000 Grenoble, France.
authors.forename: Rémy
authors.initials: R
authors.lastname: Slama
authors.affiliation: Office of Research and Development, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27709, USA.
authors.forename: Danelle T
authors.initials: DT
authors.lastname: Lobdell
authors.affiliation: Department of Family and Preventive Medicine, University of Utah, Salt Lake City, UT 84108, USA.
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Stanford
authors.affiliation: Department of Growth and Reproduction and EDMaRC, University of Copenhagen, Rigshospitalet, DK-2100 Copenhagen, Denmark.
authors.forename: Tina Kold
authors.initials: TK
authors.lastname: Jensen
authors.affiliation: Department of Sociology and College of Law, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Elizabeth Heger
authors.initials: EH
authors.lastname: Boyle
authors.affiliation: Department of Urology, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Eisenberg
authors.affiliation: The Turek Clinic, Beverly Hills, CA 90210, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Turek
authors.affiliation: Biostatistics and Bioinformatics Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20829, USA.
authors.forename: Rajeshwari
authors.initials: R
authors.lastname: Sundaram
authors.affiliation: Department of Family Science, School of Public Health, University of Maryland, College Park, MD 20742, USA.
authors.forename: Marie E
authors.initials: ME
authors.lastname: Thoma
authors.affiliation: Office of the Director, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 6710B Rockledge Dr. Room 3131A, Bethesda, MD 20829, USA.
authors.forename: Germaine M
authors.initials: GM
authors.lastname: Buck Louis
mesh_terms: D001723:Birth Rate; D005260:Female; D005298:Fertility / Q000502:physiology*; D006801:Humans; D008297:Male; D011247:Pregnancy; D012098:Reproduction / Q000502:physiology*; D061685:Time-to-Pregnancy
keywords: epidemiology; fecundity; fertility; gynecologic diseases; time-to-pregnancy; urologic diseases