A prospective cohort study of menstrual characteristics and time to pregnancy.

The authors examined the association between menstrual characteristics and time to pregnancy among 2,653 Danish women enrolled in a prospective cohort study (2007-2009). Menstrual characteristics were reported at baseline. Outcome data were updated bimonthly until pregnancy, fertility treatment, loss to follow-up, or end of observation (12 cycles). Adjusted fecundability ratios and 95% confidence intervals were estimated by using discrete-time Cox regression models. Relative to average cycle lengths (27-29 days), fecundability ratios for cycle lengths <25, 25-26, 30-31, 32-33, and ≥34 days were 0.64 (95% confidence interval (CI): 0.49, 0.84), 0.94 (95% CI: 0.77, 1.13), 1.10 (95% CI: 0.97, 1.25), 1.35 (95% CI: 1.06, 1.73), and 1.17 (95% CI: 0.91, 1.49), respectively. Compared with cycles that regularized within 2 years after menarche, fecundability ratios for cycles that regularized 2-3 and ≥4 years after menarche were 0.90 (95% CI: 0.80, 1.02) and 0.89 (95% CI: 0.77, 1.03), respectively. Fecundability ratios were 0.87 (95% CI: 0.72, 1.05) comparing <3 with 3-4 days of menstrual bleeding and 0.70 (95% CI: 0.43, 1.13) comparing very heavy with moderate flow. In the present study, shorter cycle length was associated with delayed time to pregnancy. Age at menarche, time to menstrual regularization, and duration or intensity of menstrual flow were not appreciably associated with fecundability.

[1]  C. Weinberg,et al.  Accuracy of reporting of menstrual cycle length. , 2007, American journal of epidemiology.

[2]  D. Baird,et al.  Influence of Medical Conditions and Lifestyle Factors on the Menstrual Cycle , 2002, Epidemiology.

[3]  D. Apter,et al.  Endocrine characteristics of adolescent menstrual cycles: impact of early menarche. , 1984, Journal of steroid biochemistry.

[4]  J. Reif,et al.  Reliability of retrospectively assessed categorical menstrual cycle length data. , 2009, Annals of epidemiology.

[5]  S. Henshaw,et al.  Unintended Pregnancy, Contraceptive Practice and Family Planning Services in Developed Countries , 1988 .

[6]  Henrik Toft Sørensen,et al.  The Danish National Birth Cohort - its background, structure and aim , 2001, Scandinavian journal of public health.

[7]  Kenneth J Rothman,et al.  Randomized trial of questionnaire length. , 2009, Epidemiology.

[8]  A. Wilcox,et al.  Validity issues relating to time-to-pregnancy studies of fertility. , 2006, Epidemiology.

[9]  P. Braverman,et al.  Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign , 2016, Pediatrics.

[10]  E. Porcu,et al.  Longitudinal evaluation of the different gonadotropin pulsatile patterns in anovulatory cycles of young girls. , 1992, The Journal of clinical endocrinology and metabolism.

[11]  Fecundability in relation to body mass and menstrual cycle patterns. , 1999 .

[12]  Henrik Toft Sørensen,et al.  A successful implementation of e-epidemiology: the Danish pregnancy planning study ‘Snart-Gravid’ , 2010, European Journal of Epidemiology.

[13]  S. Harlow,et al.  Epidemiology of menstruation and its relevance to women's health. , 1995, Epidemiologic reviews.

[14]  Worldhealthorganizationtaskfo.  World Health Organization multicenter study on menstrual and ovulatory patterns in adolescent girlsII. Longitudinal study of menstrual patterns in the early postmenarcheal period, duration of bleeding episodes and menstrual cycles , 1986 .

[15]  L Frank,et al.  When an Entire Country Is a Cohort , 2000, Science.

[16]  N. Best,et al.  Studying time to pregnancy by use of a retrospective design. , 2005, American journal of epidemiology.

[17]  W. Tierney,et al.  Multiple imputation in public health research , 2001, Statistics in medicine.

[18]  M. Blythe,et al.  Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign , 2006, Pediatrics.

[19]  Mary Schneider,et al.  Variability in the phases of the menstrual cycle. , 2006, Journal of obstetric, gynecologic, and neonatal nursing : JOGNN.

[20]  I. Hertz-Picciotto,et al.  Incidence of early loss of pregnancy. , 1988, The New England journal of medicine.

[21]  T. K. Jensen,et al.  Menstrual cycle pattern and fertility: a prospective follow-up study of pregnancy and early embryonal loss in 295 couples who were planning their first pregnancy. , 1999, Fertility and sterility.

[22]  A. Manatunga,et al.  Validity of self-reported menstrual cycle length. , 2007, Annals of epidemiology.

[23]  L. Signorello,et al.  Factors associated with early menopause. , 2000, Maturitas.

[24]  O. Widholm,et al.  A statistical analysis of the menstrual patterns of 8,000 Finnish girls and their mothers. , 1971, Acta obstetricia et gynecologica Scandinavica. Supplement.

[25]  A. Treloar,et al.  Variation of the human menstrual cycle through reproductive life. , 1967, International journal of fertility.

[26]  J. Palmer,et al.  Follow-up of a large cohort of Black women. , 2001, American journal of epidemiology.

[27]  D. Apter,et al.  Early menarche, a risk factor for breast cancer, indicates early onset of ovulatory cycles. , 1983, The Journal of clinical endocrinology and metabolism.

[28]  Per Magnus,et al.  Self-selection and bias in a large prospective pregnancy cohort in Norway. , 2009, Paediatric and perinatal epidemiology.

[29]  L. Chiazze,et al.  The length and variability of the human menstrual cycle. , 1968, JAMA.

[30]  V. Vitzthum,et al.  Vaginal bleeding patterns among rural highland Bolivian women: relationship to fecundity and fetal loss. , 2001, Contraception.

[31]  E. Lenton,et al.  Normal variation in the length of the follicular phase of the menstrual cycle: effect of chronological age , 1984, British journal of obstetrics and gynaecology.

[32]  M. Melbye,et al.  Maternal risk of breast cancer and birth characteristics of offspring by time since birth. , 1999, Epidemiology.

[33]  S. Swan,et al.  Ovarian Hormones in Premenopausal Women: Variation by Demographic, Reproductive and Menstrual Cycle Characteristics , 2002, Epidemiology.

[34]  B E Ainsworth,et al.  A simultaneous evaluation of 10 commonly used physical activity questionnaires. , 1993, Medicine and science in sports and exercise.

[35]  D D Baird,et al.  Use of time to pregnancy to study environmental exposures. , 1986, American journal of epidemiology.

[36]  A. Byskov,et al.  Characteristics of human ovulation in natural cycles correlated with age and achievement of pregnancy. , 2001, Human reproduction.

[37]  N. Keiding,et al.  Maternal risk of breast cancer and birth characteristics of offspring by time since birth. , 1999 .

[38]  R. Barbieri,et al.  Determinants of basal follicle-stimulating hormone levels in premenopausal women. , 1994, The Journal of clinical endocrinology and metabolism.

[39]  G. Zielhuis,et al.  THE INFLUENCE OF OCCUPATIONAL PHYSICAL ACTIVITY ON THE MENSTRUAL CYCLE AND FECUNDABILITY , 1994, Epidemiology.

[40]  Henrik Toft Sørensen,et al.  An internet-based prospective study of body size and time-to-pregnancy. , 2010, Human reproduction.

[41]  E. Porcu,et al.  Postmenarchal evolution of endocrine pattern and ovarian aspects in adolescents with menstrual irregularities. , 1987, Fertility and sterility.

[42]  Mitchel Klein,et al.  Menstrual Cycle Characteristics: Associations With Fertility and Spontaneous Abortion , 2006, Epidemiology.

[43]  W J Bremner,et al.  Reproductive aging: accelerated ovarian follicular development associated with a monotropic follicle-stimulating hormone rise in normal older women. , 1996, The Journal of clinical endocrinology and metabolism.

[44]  J. Liss,et al.  Effect of short follicular phase with follicular maturity on conception outcome. , 2003, Clinical and experimental obstetrics & gynecology.

[45]  R. Simon,et al.  Flexible regression models with cubic splines. , 1989, Statistics in medicine.

[46]  Henrik Toft Sørensen,et al.  Cohort profile: the Danish Web-based Pregnancy Planning Study--'Snart-Gravid'. , 2009, International journal of epidemiology.

[47]  K. Münster,et al.  Length and variation in the menstrual cycle—a cross‐sectional study from a Danish county , 1992, British journal of obstetrics and gynaecology.

[48]  J. LaFountain.  Inc. , 2013, American Art.

[49]  M. Frydenberg,et al.  Does Low Participation in Cohort Studies Induce Bias? , 2006, Epidemiology.

[50]  S. Swan,et al.  Use of urine biomarkers to evaluate menstrual function in healthy premenopausal women. , 1998, American journal of epidemiology.