The plight of nuns: hazards of nulliparity

Abstract

Women experiencing menarche before age 12 years had a slightly higher risk of breast cancer than did those who were older than 15 at menarche.5 Similarly, the risk of breast cancer is increased by 17% for every 5-year delay in menopause.6 Bilateral oophorectomy before age 40 years led to a 45% reduced risk of breast cancer compared with women with a natural menopause at ages 50-54 years.5 The increased number of cycles between menarche and menopause also leads to increased risk of ovarian and uterine cancers.7,8 This finding has been best shown by Eaton and colleagues' mathematical model,9 which used age at menarche, first pregnancy and menopause, and use of oral contraceptives to predict incidence of a woman's reproductive cancer.