The Adolescent Brain Cognitive Development (ABCD) Study® is the largest long-term study of brain development and child health in the United States. The National Institutes of Health (NIH) funded leading researchers in the fields of adolescent development and neuroscience to conduct this ambitious project. The HEALthy Brain and Child Development (HBCD) Study will recruit a large cohort of pregnant women from regions of the country significantly affected by the opioid crisis and follow them and their children through early childhood. The study will collect information beginning at birth and continuing through early childhood, including structural and functional brain imaging; anthropometrics; medical history; family history; biospecimens; and social, emotional, and cognitive development.