Area-Level and Individual-Level Factors for Teenage Motherhood: A Multilevel Analysis in Japan

BACKGROUND Teenage motherhood is strongly associated with a range of disadvantages for both the mother and the child. No epidemiological studies have examined related factors for teenage motherhood at both area and individual levels among Japanese women. Therefore, we performed a multilevel analysis of nationwide data in Japan to explore the association of area- and individual-level factors with teenage motherhood. METHODS The study population comprised 21,177 mothers living in 47 prefectures who had their first, singleton baby between 10 and 17 January or between 10 and 17 July, 2001. Information on the prefecture in which the mothers resided was linked to prefecture-level variables. Primary outcomes were area-level characteristics (single-mother households, three-generation households, college enrollment, abortions, juvenile crime, and per capita income) and individual-level characteristics, and divided into tertiles or quintiles based on their variable distributions. Multilevel logistic regression analysis was then performed. RESULTS There were 440 teenage mothers (2.1%) in this study. In addition to individual low level of education [adjusted odds ratio (OR), 7.40; 95% confidence interval (CI), 5.59-9.78], low income [4.23 (2.95-6.08)], and smoking [1.65 (1.31-2.07)], high proportions of single-mother households [1.72 (1.05-2.80)] and three-generation household [1.81 (1.17-2.78)], and per capita income [2.19 (1.06-3.81)] at an area level were positively associated, and high level of college enrollment [0.46 (0.25-0.83)] and lower crime rate [0.62 (0.40-0.98)] at area level were inversely associated with teenage motherhood compared with the corresponding women living in prefectures with the lowest levels of these variables. CONCLUSIONS Our findings suggest that encouraging the completion of higher education and reducing the number of single-mother household at an area level may be important public health strategies to reduce teenage motherhood.