Female-specific hypertension risk factors across the lifecourse: a co-twin control analysis using the California Twin Program

Twin studies have been underutilized for examining female-specific etiology of hypertension (HT). The discordant co-twin design offers unique strengths not afforded by other approaches primarily because relatedness and shared origins naturally match twin pairs more closely on genetic and early environmental confounders. We aimed to confirm HT-associated factors across the lifecourse among 202 female twin pairs identified from the California Twin Program (CTP) registry. A baseline questionnaire queried current and past risk factors and self-reported prevalent HT. HT-discordant pairs were compared for differences in demographics, growth and body size, reproductive factors, and lifestyle factors. Data were analyzed using conditional logistic regression restricted to nonsmokers and stratified by zygosity. Weighing ≥150lbs. versus <130lbs. at 18 years was associated with 3-fold odds of HT, and weighing ≥180lbs. at the time of questionnaire was associated with 6-fold odds of HT. Exercising more than one's co-twin was associated with 0.54-fold odds of HT. Menopause was positively associated with HT, with post-menopausal DZ twins experiencing 4-fold odds of HT compared to pre-menopausal co-twins. This study with minimal bias using unaffected co-twins confirmed multiple factors associated with female HT including overweight at age 18 and in adulthood, lower level of exercise, and menopausal.