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How regular is regular? An analysis of menstrual cycle regularity
Mitchell D Creinin1, Sharon Keverline, Leslie A Meyn
1Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Magee Womens Research Institute, 300 Halket Street, Pittsburgh, PA 15213-3180, USA. mcreinin@mail.magee.edu
Contraception
|September 29, 2004
Summary
Women accurately estimate their average menstrual cycle length, but significant cycle variability exists. This variability impacts contraceptive use, research, and pregnancy care.
Area of Science:
- Reproductive Health
- Women's Health
- Clinical Research
Background:
- Women often report regular menstrual cycles.
- Accurate perception of menstrual cycle length is crucial for reproductive health management.
Purpose of the Study:
- To assess the accuracy of women's self-estimated menstrual cycle length compared to actual measured lengths.
- To quantify the variability in menstrual cycle length among women reporting regular cycles.
Main Methods:
- Retrospective analysis of data from three barrier contraceptive studies.
- Included 130 women (18-40 years) with self-reported regular cycles (21-35 days).
- Compared estimated cycle length to prospectively recorded actual cycle lengths over up to 30 weeks.
Main Results:
- Average estimated cycle length closely matched average actual cycle length (29.0 vs. 29.1 days).
- Significant cycle variability was observed: 46% had a range of ≥7 days, 20% had a range of ≥14 days.
- Average menses duration (5.2 days) positively correlated with actual cycle length in women with 21-35 day cycles.
Conclusions:
- While women's average perception of cycle length is accurate, substantial individual cycle variability exists.
- This menstrual cycle variability has potential clinical implications for contraception, research, and pregnancy care.