Objective: To investigate the association between early age at menarche and blood pressure in Chinese girls aged 7 to 17 years.
Methods: A total of 76 869 girls aged 7 to 17 years old were selected from the national physical fitness and health research in 2010, and probit analyses were used to calculate the average age of menarche for each province. Girls whose age were lower than the P 10 of age at menarche were judged as early age at menarche, and matched with two selected participant without menarche based on the age and the same urban or rural areas. High blood pressure was defined as whose systolic pressure and/or diastolic pressure was higher than P 95 of systolic pressure or diastolic pressure at the same age group. The difference of the rate of high blood pressure in girls with and without menarche by Chi-square test, and multilevel model was used to analyze the relationship between early age at menarche and blood pressure.
Results: In 76 869 girls, the values of height and BMI were separately (152.2 ± 10.4) cm and (18.7 ± 3.1) kg/m(2), while the systolic pressure and diastolic pressure were (103.4 ± 11.0) mm Hg (1 mm Hg = 0.133 kPa) and (65.0 ± 9.1) mm Hg respectively. In 47 942 girls (62.4%) had occurred menstruation while 28 927 girls (37.6%) without menstruation. The girls began to report menstruation at the age of 9, and 81.5% (7123/8736) girls had already reported menstruation at the age of 13. The rate of high blood pressure in menstruation group from 11 to 13 years were separately 6.71% (100/1490), 5.99% (265/4423) and 5.38% (383/7123), which was significant higher than 3.78% (265/7005), 3.33% (144/4328) and 4.09% (66/1613) in the same age group of non-menstruation (the values of Chi-square were separately 25.62, 32.36, 4.46, and all P values < 0.05) . The mean age of early age at menarche was 9 to 11 years old, and the rate of high blood pressure, high systolic pressure, and high diastolic pressure at 11 years group was separately 6.08% (49/806), 4.84% (39/806) and 3.35% (27/806), which was significant higher than that in non-menstruation group (separately 3.11% (50/1607), 2.30% (37/1607) and 1.43% (23/1607), and the values of Chi-square were separately 12.02, 11.32 and 9.74, while all P values <0.01). After adjusted by region and age, early age at menarche were separately associated with the rate of high blood pressure (OR = 2.188; 95%CI: 1.254-3.818), high systolic pressure (OR = 1.925; 95%CI:1.097-3.379) and high diastolic pressure (OR = 2.088; 95%CI: 1.072-4.065).
Conclusion: Early age at menarche may be one of the influence factors of high blood pressure, which may contribute to early age of high blood pressure in Chinese children and adolescents.