J. Auger, J. Kunstmann, F. Czyglik, and P. Jouannet, Decline in semen quality among fertile men 3

O. Basso, S. Juul, and J. Olsen, Time to pregnancy as a correlate of fecundity

A. Giwercman, J. Olsen, and N. Skakkebaek, Relation between semen quality and fertility: a 12 population-based study of 430 first-pregnancy planners, Lancet, vol.352, pp.1172-1177, 1998.

N. Skakkebaek, A. Andersson, and J. Olsen, A follow-up study of environmental and 15 biologic determinants of fertility among 430 Danish first-pregnancy planners: design 16 and methods, Reprod Toxicol, vol.12, pp.19-27, 1998.

S. Schrader, Prospective pregnancy study designs for assessing reproductive and 19 developmental toxicants, Environ Health Perspect, vol.112, pp.79-86, 2004.

E. Carlsen, A. Giwercman, N. Keiding, and N. Skakkebaek, Evidence for decreasing quality of semen during past 50 years., BMJ, vol.305, issue.6854, pp.609-613, 1992.
DOI : 10.1136/bmj.305.6854.609

B. Cohn, J. Overstreet, R. Fogel, C. Brazil, D. Baird et al., Epidemiologic Studies of Human Semen Quality: Considerations for Study Design, American Journal of Epidemiology, vol.155, issue.7, pp.664-688, 2002.
DOI : 10.1093/aje/155.7.664

J. Auger and P. Jouannet, Regional differences in waiting time to pregnancy among 18 couples from four European cities, Human Reproduction, vol.16, pp.2697-2704, 2001.

T. Jensen, M. Joffe, T. Scheike, A. Skytthe, D. Gaist et al., Time trends in waiting time to pregnancy among Danish twins, Human Reproduction, vol.20, issue.4, pp.955-964, 2005.
DOI : 10.1093/humrep/deh723

M. Joffe, Time trends in biological fertility in Britain, The Lancet, vol.355, issue.9219, pp.1961-1983, 1965.
DOI : 10.1016/S0140-6736(00)02328-X

M. Joffe, J. Key, N. Best, N. Keiding, T. Scheike et al., Studying time to pregnancy by use 24 of a retrospective design, Am J Epidemiol Human reproduction, vol.16224, pp.115-1241999, 2005.

N. Jorgensen, C. Asklund, E. Carlsen, and N. Skakkebaek, Coordinated European investigations of semen quality: results from studies of Scandinavian young men is a matter of concern, International Journal of Andrology, vol.19, issue.1, pp.54-61, 2006.
DOI : 10.1111/j.1365-2605.2005.00523.x

S. Juul, W. Karmaus, and J. Olsen, Regional differences in waiting time to pregnancy: pregnancy- 6 based surveys from Denmark, France

W. Karmaus and S. Juul, on behalf of the European infertility and subfecundity study group

N. Keiding, Independent delayed entry (with discussion), p.12
DOI : 10.1007/978-94-015-7983-4_18

N. Keiding, K. Kvist, H. Hartvig, M. Tvede, and S. Juul, Estimating time to pregnancy from current durations in a cross-sectional sample, Biostatistics, vol.3, issue.4, pp.565-578, 2002.
DOI : 10.1093/biostatistics/3.4.565

J. Key, N. Best, M. Joffe, T. Jensen, and N. Keiding, Methodological issues in analyzing time 16 trends in biologic fertility: protection bias, American journal of epidemiology, vol.17169, pp.285-293, 2009.

U. Larsen and J. Vaupel, Hutterite Fecundability by Age and Parity: Strategies for Frailty Modeling of Event Histories, Demography, vol.30, issue.1, pp.81-102, 1993.
DOI : 10.2307/2061864

H. Leridon, Sterility and Subfecundity: from silence to impatience. Population: an English 21 selection, pp.35-54, 1992.

H. Leridon, Studies of fertility and fecundity: comparative approaches from demography and epidemiology, Comptes Rendus Biologies, vol.330, issue.4, pp.339-346, 2007.
DOI : 10.1016/j.crvi.2007.02.013
URL : https://hal.archives-ouvertes.fr/inserm-00150962

H. Leridon and R. Slama, The impact of a decline in fecundity and of pregnancy postponement on help?, Fertil Steril, vol.93, pp.737-744, 2010.

D. Lannou, J. Guerin, M. Benchaib, and R. Slama, Selection bias in semen studies due 4 to self-selection of volunteers, Hum Reprod, vol.19, pp.2838-2844, 2004.

J. Guerin, M. Benchaib, and A. Spira, Geographic variations in probability of pregnancy in 7 four cities of France, Rev Epidemiol Sante Publique, vol.54, pp.55-60, 2006.

C. Nelson and R. Bunge, Semen Analysis: Evidence for Changing Parameters of Male Fertility Potential, Fertility and Sterility, vol.25, issue.6, pp.503-507, 1974.
DOI : 10.1016/S0015-0282(16)40454-1

J. Olsen and P. Andersen, We Should Monitor Human Fecundity, But How? A Suggestion for a New Method That May Also Be Used to Identify Determinants of Low Fecundity, Epidemiology, vol.10, issue.4, pp.419-421, 1999.
DOI : 10.1097/00001648-199907000-00013

J. Olsen and P. Rachootin, Invited commentary, Journal of the American College of Surgeons, vol.199, issue.6, p.14
DOI : 10.1016/j.jamcollsurg.2004.08.014

M. Sallmen, M. Lindbohm, and M. Nurminen, Paternal Exposure to Lead and Infertility, Epidemiology, vol.11, issue.2, pp.148-152, 2000.
DOI : 10.1097/00001648-200003000-00011

M. Sallmen, D. Baird, A. Wilcox, C. Weinberg, and M. Lindbohm, Human Fertility Decline?, Epidemiology, vol.17, issue.2, pp.238-239, 2006.
DOI : 10.1097/01.ede.0000199517.66134.3e

T. Scheike, L. Rylander, L. Carstensen, N. Keiding, T. Jensen et al., Time Trends in Human Fecundability in Sweden, Epidemiology, vol.19, issue.2, pp.191-196, 2008.
DOI : 10.1097/EDE.0b013e31816334ad

R. Slama, T. Kold-jensen, T. Scheike, B. Ducot, A. Spira et al., How would a decline in 24 sperm concentration over time influence the probability of pregnancy? Epidemiology Bouyer J. Feasibility of the Current-Duration Approach to Studying Human Fecundity

R. Slama, O. Boutou, B. Ducot, and A. Spira, Reproductive life events in the population living in the vicinity of a nuclear waste reprocessing plant, Journal of Epidemiology & Community Health, vol.62, issue.6, pp.513-521, 2008.
DOI : 10.1136/jech.2007.061069
URL : https://hal.archives-ouvertes.fr/inserm-00284287

R. Slama, B. Ducot, N. Keiding, B. Blondel, and J. Bouyer, Bulletin 7

E. Stephen and A. Chandra, Declining estimates of infertility in the United States, pp.1982-2002

S. Swan, E. Elkin, and L. Fenster, The Question of Declining Sperm Density Revisited: An 11

C. Tietze, Fertility after discontinuation of intrauterine and oral contraception, Int J Fertil, vol.1413, pp.385-389, 1968.

B. Van-es, C. Klaassen, and K. Oudshoorn, Survival analysis under cross-sectional sampling: length bias and multiplicative censoring, Journal of Statistical Planning and Inference, vol.91, issue.2, pp.295-312, 2000.
DOI : 10.1016/S0378-3758(00)00183-X

C. Weinberg and B. Gladen, The Beta-Geometric Distribution Applied to Comparative Fecundability Studies, Biometrics, vol.42, issue.3, pp.547-560, 1986.
DOI : 10.2307/2531205

C. Weinberg, D. Baird, and A. Wilcox, Sources of bias in studies of time to pregnancy, Statistics in Medicine, vol.84, issue.5-7
DOI : 10.1002/sim.4780130528

A. Wilcox, C. Weinberg, O. Connor, J. Baird, D. Schlatterer et al., Incidence of Early Loss of Pregnancy, New England Journal of Medicine, vol.319, issue.4, pp.189-194, 1988.
DOI : 10.1056/NEJM198807283190401

L. Wise, K. Rothman, E. Mikkelsen, H. Sorensen, A. Riis et al., An internet-based 24 prospective study of body size and time-to-pregnancy Human reproduction