A one-year observational cohort study of menstrual cramps and ovulation in healthy, normally ovulating women

This is a prospective, observational community cohort study with the objective of investigating menstrual cramp occurrence related to ovulatory characteristics. Women reported cramp intensity on daily Menstrual Cycle Diary© records over one year. Ovulation and luteal phase lengths were assessed by validated Quantitative Basal Temperature© (QBT) analysis. Healthy, normal-weight, non-smoking community dwelling premenopausal women ages 21–41 years with two consecutive, normally ovulatory, normal-length menstrual cycles were enrolled. All 53 women, with 13.6 ± 2.8 cycles per woman, reported at least one cramp episode of median intensity 1.5 [0–4 scale; range 1.0–3.5], and 2.2 days’ [range 1.0–10.2] duration. Within the 49 women who experienced all ovulatory cycle types (normal, short luteal length [SLL < 10 days] and anovulatory), median cramp intensity was greater in normal-length cycles having subclinical ovulatory disturbances (SLL and anovulatory; median 1.4 [range 0.0–2.8]) than in normally ovulatory cycles (median 1.2 [range 0.0–2.3]) (P = 0.023). Cramp Scores did not differ by ovulatory status within the 19 women having both normally ovulatory and anovulatory cycles (P = 0.222). Within-woman 1-year Cramp Scores were not different in anovulatory and normally ovulatory menstrual cycles but were more intense with ovulatory disturbances.