Adolescent motherhood and socioeconomic factors: An ecologic approach

Several ecologic studies have stressed the association between adolescent fertility and socioeconomic indicators, yet the true magnitude of the association and the intermediate factors involved remain unclear. The objectives were to describe in an urban context the ecologic association between the adolescent (15-19 year olds) fertility rates distribution and trends and to compare the effect of using different aggregates. The results show that the adolescent fertility rates distribution and trends between 1980 and 1992 in 10 Barcelona districts parallel the socioeconomic distribution as measured by a socioeconomic index (average family income index). The average family income index is negatively associated with fertility rates, with Pearson coefficients of -0.78 and 0.67 at the district and neighbourhood levels respectively. Within Spain, using local (Barcelona's districts or neighbourhoods) or regional (province or communities) aggregates yields a different degree of ecologic association, with local analysis giving a higher ratio between the highest and lowest rates (1:34.1 at the neighbourhood level, 1:3.2 at the community level) and a higher correlation with income (- 0.70 at the neighbourhood level, -0.82 at the district level), which is lower and statistically non-significant at the province or community level. This study supports the use of the smaller available units of analysis in ecologic studies. The influence of ecologic bias and the potential role of socioeconomic factors leading to pregnancy and childbearing among adolescents are discussed.