Incidence of ovulation from the menarche to the menopause: observations of 622 New Zealand women
Metcalf, M.G.
New Zealand Medical Journal 96(738): 645-648
1983
ISSN/ISBN: 0028-8446 PMID: 6576257 Document Number: 211341
Urine samples were collected once weekly for two to four months from 622 normal women. Menstrual cycles were considered to be ovulatory if the 24 h pregnanediol output in the 12 days preceding menstruation was greater than or equal to 5 mumol on one occasion, or if the total excreted on two occasions, one week apart, was greater than or equal to 7 mumol. The incidence of ovulatory cycles increased from 48% in girls aged 10-14 yr to 72% by 20-24 yr, reached a plateau of 98% in women aged 30-39 yr, then declined with the approach of the menopause to 66% in women over the age of 50 yr. In women who were 5-8 yr from the menarche, departure from the parental home was associated with a decline in ovulatory incidence (84% for women living with parents, cf 46% for women living in flats and hostels; p less than 0.01). A similar decline was noted in women over the age of 40 yr who had experienced a break in a previously regular pattern of menstrual cycles (98% for women with regular cyclicity, cf 58% for women with variable cyclicity; p less than 0.001). Hormone patterns consistent with the occurrence of ovulation were seen at all stages from 120 days after the menarche to seven days before the menopause.