| Description |
In human females, cyclic luteinizing hormone surge and ovulation occurrence are orchestrated by a complex sequence of events within the body relatively independently of external stimuli. This coordinated system of cyclic hormonal changes and events is known as the menstrual cycle. It is repeated up to about 500 times over a healthy woman's 35-40 year reproductive lifespan, a biologic vital sign of a woman's reproductive health. In a normal menstrual cycle, there are specific symptoms and events, unique to different phases of a menstrual cycle, that can be observed and recorded objectively by women. It is important for both patients and their clinicians to have a solid understanding of menstrual cycle characteristics and their normal variabilities. Combined data from 3 cohorts, followed up to 1 year, were utilized to assess menstrual cycle variability within and between 3,326 cycles of 582 women aged 18-40, with no known subfertility, not currently taking any exogenous hormones, who used a standardized protocol to observe, record, and interpret vaginal discharges. There were significant differences in menstrual cycle characteristics by age and parity. Parous women had parameters more associated with fecundity than nulliparous women, including more days of peak-type mucus, fewer dry (no mucus) days, a higher cervical mucus cycle score, and fewer of nonfertile days. Nulliparous women <30 years compared to nulliparous women ≥30 had better fecundity indicators, including a higher number of potentially fertile days. These women had substantial variability of menstrual cycle characteristics over a period of 1 year. This variability may reflect the female reproductive system's sensitivity to emotional as well as environmental influences. In cycles with at least 1 day of intercourse compared to cycles lacking any intercourse among the same sexually active women, there were indicators of higher fecundity, including longer luteal phases, fewer deficient luteal phases, lower incidence of luteal spotting, and fewer cycles with <2 days of highly estrogenic (peak-type) cervical mucus secretion. Women's reproductive health can be enhanced by the assessment of a woman's menstrual cycle pattern by clinicians and by the woman herself. Future work should investigate the impact of subfertility and gynecologic conditions. |
