Urine for the analysis of pregnanediol was collected weekly for 3 months from 209 menstruant women aged 11–24 years who lived with their parents and from 59 women aged 17–23 years who had left the parental home. Menstrual cycles were classed as ovulatory if the 24-h pregnanediol output in the 12 days preceding menstruation was ≥ 5 μmol on a single occasion or if the total excreted on 2 days, 1 week apart, was ≥ 7 μmol.
In the first group, ovulatory incidence increased with menarchal age. Unfailing ovulation occurred in 22·9, 25·0,44·8,42·9, 63·2, 71·8 and 82·6% of those who were < 1, 1−<2, 2−<3, 3−<4, 4−< 5, 5–8 and 9–12 years from menarche. Comparable figures for the women who lived in flats and hostels were 40·0% (menarchal age, 5–8 years) and 78·6% (9–12 years).
It is concluded that a regular pattern of ovulatory menstrual cycles is established in most young women within 5 years of the menarche, and that departure from the family home is often associated with a regression to a juvenile pattern of anovulatory menstrual cycles.