Mediation Effect of Obesity on the Association of Age at Menarche With Blood Pressure Among Women in Southwest China.

Background Previous studies have been inconsistent about the association between age at menarche and high blood pressure. Little is known about such association across a wide range of menarcheal ages in less developed ethnic minority regions in China. We aimed to explore the association between age at menarche and high blood pressure (BP; ≥140/90 mm Hg) and to examine the mediating effect of obesity and the moderating effect of menopausal status on this association. Methods and Results A total of 45 868 women from the baseline data of the CMEC (China Multi-Ethnic Cohort) were included in this study. Binary logistic regression was used to analyze the relationship between age at menarche and high BP, and the mediation model was used to evaluate the mediating effects of body mass index and waist circumference on the association of age at menarche with high BP. The mean age at enrollment and age at menarche of participants in our study were 49.3 (SD=10.7) and 14.7 (SD=2.1) years, respectively. Late menarche was associated with a lower risk of high BP (odds ratio, 0.831 [95% CI, 0.728-0.950]). The risk of high BP decreased by 3.1% with each year's delay in the onset of menarche ( P for trend <0.001). Body mass index and waist circumference could partially mediate the association of age at menarche and high BP with the indirect effect of body mass index (odds ratio, 0.998 [95% CI, 0.997-0.998]) and waist circumference (odds ratio, 0.999 [95% CI, 0.998-0.999]). In addition, the mediation effects were modified by the status of menopause. Conclusions Women with late menarche have a lower risk of high BP, and obesity could be one of the important mediators. Obesity prevention is an efficient strategy to reduce the association between age at menarche and high BP, especially in premenopausal women.