Risk of breast cancer in prematurely born women

After inspecting 60,000 charts from Swedish children born between 1925 et 1934, the authors identified 273 girls born before 35 weeks' gestation or who weighed less than 2,000g. The breast cancer risk in women born before 31 weeks' gestation was 6.7 times that of the general population. Women born at 31 to 32 weeks had a 2- to 4- increase in risk. Women born after the 34th week who weighed less than 2,000 g at birth appeared to have a lower risk of breast cancer, in agreement with other studies.