Combined effect of weight gain within normal weight range and parental hypertension on the prevalence of hypertension; from the J-MICC Study

The aim of this study is to show the combined effect of weight gain within normal weight range in adulthood and parental HT on the prevalence of HT. The study subjects were 44,998 individuals (19,039 men and 25,959 women) with normal weight (body mass index [BMI] 18.5–24.9) aged 35–69 years who participated in the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study. They were categorized into six groups by weight gain from age 20 years (<10 kg, and ≥10 kg) and by the number of parents having HT (no parent, one parent, and both parents). Odds ratios for HT were estimated after adjustment for age, sex, current BMI, estimated daily sodium intake, and other confounding factors. The prevalence of HT (31.5% in total subjects) gradually increased with greater weight gain from age 20 years and with greater number of parents with HT. Subjects who gained weight ≥10 kg and having both parents with HT showed the highest risk of having HT compared with those who gained weight <10 kg without parental HT (59.8% vs. 24.9%, odds ratio 4.25, 95% CI 3.53–5.13 after adjustment). This association was similarly observed in any category of age, sex, and BMI. Subjects who gained weight within normal range of BMI and having one or both parent(s) with HT showed the higher risk of having HT independent of their attained BMI in their middle ages. Thus, subjects having parent(s) with HT should avoid gaining their weight during adulthood, even within normal range of BMI, to reduce the risk of having HT.