Printed in Great Britain Level of Education, Use of Oral

High social class has been linked to increased risk of breast cancer. The present study elaborates the associations between a frequently-used indicator of social class, length of education, and some reproductive factors associated with risk of breast cancer (age at menarche, the number of children, age at first pregnancy and use of oral contracep-tives) in 8030 women in Troms0, Norway. We found a weak negative association between level of education and age at menarche and a stronger negative association with parity. Women with high level of education tended to have their first pregnancy relatively late in life and more frequently reported ever use of oral contraceptives. These relationships support the notion that the difference in the incidence of breast cancer between women with high and low social class may be due to reproductive factors. Both social class and reproductive factors (eg, age at menarche and menopause, the number of children and the age at each delivery) are established as factors of major importance for the risk of breast cancer.1 The risk of breast cancer is increased in women in the higher social classes, and in women with early men-arche, late menopause and few children, particularl