Incidence of ovulatory cycles in women approaching the menopause

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Abstract
Summary: Urine was collected at weekly intervals at weekly intervals for three or more months from 139 menstruant women aged 40–55 years. Menstrual cycles were classed as ovulatory if the 24-hr pregnanediol output was > 5 μmol on a single occasion, or if the total excreted on 2 days 1 week apart was > 7 μmol. Of the 81 women who reported no change in menstrual frequency, 95% ovulated in every cycle. Only 34% of the 53 with a recent history of oligomenorrhoea ovulated without fail. Ovalation occurred in 93% of all 21–35-day menstrual cycles, in 55% of 36–50-day cycles, in 40% of 51–75-day cycles and in 17% of those lasting > 76 days. Pregnanediol increases suggestive of ovulation and followed by menstruation were observed on 31 occasions after amenorrhoea of from 2 to 6 months' duration.