Menstrual cycle characteristics and fecundability in a North American preconception cohort

Ann Epidemiol. 2016 Jul;26(7):482-487.e1. doi: 10.1016/j.annepidem.2016.05.006. Epub 2016 May 31.


Purpose: The aim of this study was to evaluate the association between menstrual cycle characteristics in early life and adulthood and fecundability.

Methods: Pregnancy Study Online (PRESTO) is an Internet-based preconception cohort study of pregnancy planners from the United States and Canada. During the preconception period, we enrolled 2189 female pregnancy planners aged 21-45 years who had been attempting conception for ≤6 cycles. Women self-reported menstrual cycle characteristics via an online baseline questionnaire, and pregnancy status was ascertained through bimonthly follow-up questionnaires. Proportional probabilities models were used to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs), adjusting for potential confounders.

Results: Compared with usual menstrual cycle lengths of 27-29 days, cycle lengths of <25 (FR = 0.81, 95% CI: 0.54-1.22) and 25-26 days (FR = 0.92, 95% CI: 0.75-1.14) were associated with reduced fecundability. Compared with women who reached menarche at the age of 12-13 years, those who reached menarche at <12 years had reduced fecundability (FR = 0.87, 95% CI: 0.76-0.99). Women whose cycles never regularized after menarche (FR = 0.93, 95% CI: 0.81-1.06) had slightly reduced fecundability compared with women whose cycles regularized within 2 years of menarche. Bleed length and heaviness of bleeding were not appreciably associated with fecundability.

Conclusions: Menstrual cycle characteristics, specifically cycle length and age at menarche, may act as markers of fertility potential among pregnancy planners.

Keywords: Fecundability; Menstrual cycle; Preconception cohort; Time-to-pregnancy.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Canada
  • Child
  • Cohort Studies
  • Cross-Sectional Studies
  • Female
  • Fertility / physiology*
  • Humans
  • Menstrual Cycle / physiology*
  • Middle Aged
  • North America
  • Preconception Care
  • Pregnancy
  • Pregnancy Rate*
  • Regression Analysis
  • Reproducibility of Results
  • Surveys and Questionnaires*
  • United States
  • Young Adult