PurposeThis study examined the relationships between early menarche and sexual behaviors among Korean female adolescents.MethodsWe analyzed data from the eighth Korea Youth Risk Behavior Web-based survey that was conducted on female high school students in grades 10-12. The survey included 17,867 students, and 974 students were assigned to the early menarche group because they had experienced menarche when they were in grade four or below, and 16,893 students were assigned to the normal menarche group because they had experienced menarche during or after grade five. The characteristics of the sexual behaviors in the early menarche and normal menarche group were analyzed.ResultsThe early menarche group was at a higher risk of intersexual kissing or petting (odds ratio [OR], 1.54; 95% confidence interval [CI], 1.28-1.87), intersexual intercourse (OR, 2.35; 95% CI, 1.65-3.36), homosexual kissing or petting (OR, 3.53; 95% CI, 2.22-5.59), homosexual intercourse (OR, 7.70; 95% CI, 4.04-14.66), being the victim (OR, 2.89; 95% CI, 1.98-4.22) or the assailant (OR, 13.55; 95% CI, 6.61-27.78) of sexual assaults, intercourse without any contraception (OR, 1.92; 95% CI, 1.06-3.46), and pregnancy (OR, 5.72; 95% CI, 2.31-14.15) than the normal menarche group.ConclusionEarly menarche is associated with risky sexual behaviors among adolescent females; therefore, developing comprehensive sexual health education programs and tools for early intervention are required for children who are expected to experience early menarche.

Purpose Iodine is a major component of thyroid hormones. Both deficiency and excess of iodine are major risk factors for thyroid disease, making it important to accurately assess iodine level in the human body. Urinary iodine concentration (UIC) is a commonly used measure of iodine status. However, there is little research on iodine status and related characteristics in Korean adolescents. Methods Using data from the sixth Korea National Health and Nutrition Examination Survey (KNHANES VI) for the years 2013–2015, we analyzed UIC and thyroid function test results in adolescents aged 10–18 years and their parents. We also investigated the influence of socioeconomic factors and family history of thyroid disease on iodine status. Results Mean UIC in Korean adolescents was 963.5±55.7 μg/L. Among evaluated subjects, 6.6%±1.0%, 29.8%±1.7%, and 63.9%±1.9% had low (UIC<100 μg/L), adequate (UIC: 100–299.9 μg/L), and excess (UIC≥300 μg/L) iodine concentrations, respectively. Based on regional trends, the incidence of iodine deficiency exceeded 10% in several regions, even though there was a dominance of regions with excess iodine. Parental UIC, female sex, average monthly income, and expenditure were all found to affect the iodine status of Korean adolescents. Conclusions Although regional differences exist, the iodine status in Korean adolescents is mainly affected by the eating habits of their families and socioeconomic factors. Therefore, monitoring of iodine status is necessary in this population.

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