Maternal teratogenic substances consumption during pregnancy remains poorly documented, despite its negative impact on the development of the unborn child. With vulnerable families, the risk of prenatal exposure would be such that early detection seems an urgent public health issue. This study documents such aspects with a cohort of babies (N = 340) reported to the authorities in child protection at birth. Nearly half of these children (n = 176) were exposed to alcohol or drugs during pregnancy. The links between maternal consumption, legal grounds for intervention and the placement of the child in his first three years of life are studied. Results are discussed in order to support social workers to better screen these situations and modulate their consequent interventions.