SOCIAL, BIOLOGICAL AND REPRODUCTIVE CHARACTERISTICS OF MOTHERS OF TWINS - IMPLICATIONS FOR BREAST-CANCER RISK

The biological, social and reproductive characteristics of women who h ave had twins were compared with those of other parous women using que stionnaire data gathered for a prospective cohort study of women aged 35 and over on the island of Guernsey. Data for 97 mothers of twins an d 4026 other parous women were available for analysis. The two groups were similar in height, first degree family history of breast cancer, use of hormone replacement therapy or other hormones, age at menarche, length of menstrual cycle and age at first and last birth. The mother s of twins were slightly heavier, more likely to smoke and consume mor e caffeine, less likely to have used oral contraceptives in the past, slightly younger when reaching the menopause and had a larger number o f pregnancies. Adjustment for age did not alter these results. This st udy does not provide evidence that mothers of twins differ markedly fr om other parous women across a range of characteristics that might be associated with twinning or associated with breast cancer risk.