The CHDS was originally a study which observed pregnancy, birth, and childhood growth. The study began over 40 years ago. More than 15,000 families in the Kaiser Permanente Health Plan joined the CHDS between 1959 and 1967. These landmark studies greatly advanced medical knowledge about pregnancy, childbirth, and child development. As CHDS children have become adults and started their own families, follow-up studies have looked at other health outcomes like cancer, heart disease, and lung disease. The CHDS was made possible by you, your mother, and thousands of other women and children in the East Bay. The CHDS is a project of the Public Health Institute.