Assessing the impact of adolescent pregnancy and the premarital conception stress complex on birth weight among young mothers in Gibraltar's civilian community

Purpose: The objective of this study was to assess the impact of young maternal age and the timing of conception on birth weight among primiparous women living in Gibraltar. Methods: The data for this study were derived from a population of 295 primiparous women who gave birth under 25 years of age. Only married women who had no previous maternal history and delivered live singleton newborns between 1980 and 1984 were included. The confounding effects of gestation length, sex, and socioeconomic status on birth weight were taken into account using the multivariate technique of multiple classification analysis. A conception timing variable was constructed and partitioned into four groups which represented the separate and joint effects of maternal age and prenuptial stress on birth weight. Results: The overall mean birth weight was 3344.15 g. After controlling for the specified factors and covariate, the infants of older mothers (>19) who conceived after marriage weighed 57.78 g above the referent group mean. Older mothers who conceived a child before marriage delivered infants weighing 75.67 below the grand mean. Young mothers (<20) who conceived within marriage had infants who weighed 37.32 g less than the grand mean. Infants delivered by young mothers who conceived before marriage weighed 133.66 g less than the overall mean birth weight. The only significant group difference detected within the conception timing variable was between young mothers who conceived before marriage versus older mothers who conceived after marriage. Conclusions: Premarital conception is identified as a risk factor for lower infant birth weights among mothers under 20 years of age. This study emphasizes the need to take into account the effects of culturally mediated behavior on the pregnancy experience of young women. (C) Society for Adolescent Medicine, 1997.