Breast cancer incidence following preeclampsia or gestational hypertension

Abstract

A retrospective cohort study was conducted to examine the relationship between preeclampsia or gestational hypertension and subsequent breast cancer in a population of 6,564 pregnant women. Data on the study population came from the Child Health and Development Studies, which was designed and initiated at the University of California at Berkeley between 1959 and 1966. Exposure was defined as a preeclampsia diagnosis taken from medical records and/or gestational hypertension, defined at the time of the cohort enrollment as two or more elevated blood pressure readings (>90 mm Hg diastolic or >140 mm Hg systolic) after the 20th week of gestation. Women were considered to be cases if they were diagnosed with histologically confirmed breast cancer, identified through the California Tumor Registry. Using logistic regression with data from interviews conducted during the enrollment period, analysis yielded a relative risk of breast cancer in the cohort members of 0.97 (95% CI 0.61-1.56). As the point estimate is close to 1.0 and as the confidence interval includes the null value, there is essentially no difference in breast cancer risk between the exposed and unexposed populations.