To assess prevalence and odds for teenage parenthood among former child welfare clients, we used national register data for all children born in Sweden 1972-1983 (n = 1,178,207), including 49,582 former child welfare clients with varying intervention experiences. Logistic regression models, adjusted for demographic, socio-economic and familial background factors, were used to estimate odds ratios. Among youth who received interventions in adolescence, 16-19% of the girls and 5-6% of the boys became teenage parents, compared to 3% for girls and 0.7% for boys without child welfare experiences. Youths who entered child welfare services in their teens had four- to fivefold adjusted odds for becoming a teenage parent. For other child welfare clients, adjusted odds were mostly twofold. Youth of both sexes who receive child welfare services in adolescence are a high-risk group for teenage parenthood. Child welfare agencies should, as a minimum, provide each individual client youth with access to birth control counselling and contraceptives.