Live birth records are compiled from birth certificates which are filed with the Department of Health and Senior Services by state law. The birth certificate system has been in place in Missouri continuously since 1911, although changes in data items and definitions have taken place over the years.

Live birth is defined by Missouri statute (Chapter 193, RSMo) as the complete expulsion or extraction from its mother of a child, irrespective of the duration of pregnancy, which after such expulsion or extraction, breathes or shows any other evidence of life such as beating of the heart, pulsation of the umbilical cord, or definite movement of voluntary muscles, whether or not the umbilical cord has been cut or the placenta is attached. The definition is also irrespective of birth weight.

Missouri cooperates with other states in the exchange of birth records. Therefore, data concerning births of Missouri residents include virtually all Missouri resident births regardless of where the birth took place.