Effects of age and non-hormonal contraception on menstrual cycle characteristics.

The objective of this study was to investigate the effects of age and non-hormonal contraceptive method on menstrual cycle parameters. The menstrual cycle data were collected prospectively, and the study was cross-sectional with regard to age. The subjects were 142 women, including 14 asymptomatic volunteers and 128 women who presented to a premenstrual tension (PMT) clinic. The age range was 20-45 years. Contraceptive methods used were intrauterine device (IUD) (n = 12), tubal ligation (n = 61) and non-intensive methods (n = 69). Daily menstrual cycle diaries were used to calculate cycle length and number of days of menstruation. Daily 24-h urine collections were used to calculate the day of the preovulatory estrogen peak. Pearson correlations found significant relationships between age and preovulatory estrogen peak day (p < 0.001) and length of cycle (p < 0.002), but not between age and length of menstruation or luteal phase. Analysis of variance was highly significant for age and contraceptive method, for both cycle length and preovulatory estrogen peak day. Non-intrusive contraception users aged 30 years and younger had significantly longer follicular phases than did women with tubal ligation (p < 0.05). It was concluded that cycle length decreases with age due to shortening of the follicular phase. Further research on whether tubal ligation affects ovulation and follicular phase length in young women is needed.