Association of parental characteristics with adverse outcomes of adolescent pregnancy

Background. It is well-known that pregnancy in adolescence has an increased risk of adverse reproductive outcomes. It remains unclear whether this association is due mainly to the unfavourable sociodemographic status or due solely to biological immaturity of pregnant adolescents. Objective. The purpose of this study was to determine the association of parental sociodemographic characteristics with the adverse outcomes of adolescent pregnancy. Method. Data from certificates of live births in Taichung County, Taiwan in 1994 of 7994 singleton, first-born babies whose mothers were 15-34 years of age were analysed. The relative risk of having adverse pregnancy outcomes for adolescent subgroups was obtained as compared with that among mothers 20-34 years of age with the same characteristics. The adjusted relative risk of having adverse pregnancy outcomes for each covariate was calculated by a multiple logistic regression analysis. Results. Of 7994 babies born to mothers of 15-34 years of age, 8.3% were born to adolescent mothers. In all age groups, the younger adolescent mothers (15-17 years of age) had the highest percentage of both infants with low birth weight (10.6%) and preterm births (7.1%). Younger adolescent mothers in almost all sociodemographic categories had higher risks of having both low-birth-weight and preterm births than those of older adolescent mothers. Multiple logistic regression analysis showed that a younger maternal age is the only significant risk factor for having infants with low birth weight (adjusted RR = 2.5, 95% CI 1.8-4.5 and adjusted RR = 1.7, 95% CI 1.2-2.6 for younger and older adolescent mothers, respectively) or preterm birth (adjusted RR = 1.9, 95% CI 1.1-3.4 and adjusted RR = 1.5, 95% CI 1.0-2.3 for younger and older adolescent mothers, respectively). Conclusions. Adolescent pregnancy carries an increased risk of having low-birth-weight and preterm births, and a younger maternal age is causally implicated.