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Fecundability in relation to body mass and menstrual cycle patterns
T K Jensen1, T Scheike, N Keiding
1Department of Environmental Medicine, Institute of Community Health, Winsløwparken, Denmark.
Epidemiology (Cambridge, Mass.)
|July 13, 1999
Summary
High body mass index and irregular or long menstrual cycles reduce fecundability, the ability to conceive. This study highlights factors affecting conception rates in fertile women with regular cycles.
Area of Science:
- Reproductive Endocrinology
- Human Fertility Studies
- Epidemiology
Background:
- Limited research exists on body mass index (BMI) and fecundability in women with normal menstrual cycles.
- Understanding factors influencing conception is crucial for reproductive health.
Purpose of the Study:
- To investigate the independent and combined effects of BMI, menstrual cycle duration, and regularity on fecundability.
- To quantify the impact of these factors on the odds of conception per menstrual cycle.
Main Methods:
- Retrospective cohort study using antenatal care records from Odense University Hospital, Denmark (1972-1987).
- Included 10,903 women with planned, first pregnancies and no pre-pregnancy disease.
- Calculated fecundability odds ratio (FR) adjusted for confounders.
Main Results:
- Women with BMI >25 kg/m2 had lower fecundability (FR = 0.77; 95% CI = 0.70-0.84) compared to those with BMI 20-25 kg/m2.
- Longer (>35 days) or irregular menstrual cycles were associated with reduced fecundability (FR = 0.74 and 0.78, respectively), even with normal BMI.
- Combined effects of higher BMI and irregular/long cycles further decreased conception odds.
Conclusions:
- Elevated BMI and menstrual cycle irregularities independently reduce fecundability in fertile women.
- These factors are significant considerations for women trying to conceive, even those with seemingly normal cycles.