The study assessed and compared pregnancy and child health outcomes of teenage (aged less than 20 years) and adult (20-34 years of age) mothers. A total of 226 teenage and 205 adult mothers met the study criteria out of the 3,256 women in the reproductive age group (15-49 years) and 318 adolescent girls (12-14 years of age) covered by the Nairobi Cross-sectional Slums Survey (NCSS). The main comparison involved socio-demographic variables, events during pregnancy, obstetric outcome, child morbidity and mortality and care provided during an illness episode. Results showed that a significantly higher percentage of teenage mothers and their partners had lower educational achievement compared with adult mothers and their partners. They were more likely to be economically disadvantaged than the adult mothers. Teenage mothers and their parents were also less likely to have ever been married. The two groups of mothers were comparable in terms of the rate and timing of antenatal care visits, place of delivery, rate of operative deliveries, reported size of the baby at birth, child vaccination status and reported morbidity and health care practice during an illness episode. The index child was alive during the survey period for 89.4% of the teenage and 96.6% of the adult mothers (OR = 3.36; 95% CI = 1.34, 8.79; P = 0.004). Child survival rates in the two groups of mothers were found to be quite similar after controlled analysis for the influence of socio-economic factors. The study concluded that bad obstetric outcomes were not associated with maternal age. Although teenage and adult mothers were not significantly different on child health practices, children born to the former group died most frequently probably due to their poor socioeconomic achievements.