P. Cummings et al., RISK OF BREAST-CANCER IN RELATION TO THE INTERVAL SINCE LAST FULL-TERM PREGNANCY, BMJ. British medical journal, 308(6945), 1994, pp. 1672-1674
Objective-To examine whether the risk of breast cancer is increased by
a recent term pregnancy. Design-Population based case-control study.
Setting-Eight areas in the United States. Subjects-Cases were 2279 mul
tiparous women residents of the eight areas aged 25-49 who were diagno
sed as having breast cancer during 1980-2. Controls were 2357 multipar
ous women selected from the same areas by random digit dialling. Main
outcome measure-Relative risk of developing breast cancer according to
the time interval since last full term pregnancy. Results-The distrib
ution of intervals since the last term pregnancy was similar in cases
and controls. Adjusted for age, parity, and age at first term pregnanc
y, the odds ratios observed for categories of years since the last ful
l term pregnancy were: 0-2 years, odds ratio 1.16 (95% confidence inte
rval 0.84 to 1.59); 3-6 years, odds ratio 1.21 (0.95 to 1.54); 7-9 yea
rs, odds ratio 1.04 (0.84 to 1.38); greater than or equal to 10 years,
odds ratio 1.00 (reference).Conclusions-Among multiparous women aged
25-49 years there was no association between the risk of breast cancer
and the time interval since the last full term pregnancy.