The objective of the NMIHS was to collect data needed by Federal, State, and private researchers to study factors related to poor pregnancy outcomes, including low birthweight, stillbirth, infant illness, and infant death. The NMIHS was a followback survey—it followed back to informants named on vital records. The 1988 survey expanded on information available for birth, fetal death, and infant death vital records and was the first national survey that included data on those three pregnancy outcomes simultaneously. A 1991 longitudinal follow-up to the NMIHS was conducted to obtain additional information about respondents from the 1988 survey.

The NMIHS provided data on socioeconomic and demographic characteristics of mothers, prenatal care, pregnancy history, occupational background, health status of mother and infant, and types and sources of medical care received. Data from the study may be used to evaluate factors affecting adverse outcomes of pregnancy.

The NMIHS was based on questionnaires administered to nationally representative samples of mothers with live births, stillbirths, and infant deaths during 1988 and to physicians, hospitals, and other medical care providers associated with those outcomes. The survey was based on samples of 10,000 live births, 4,000 fetal deaths, and 6,000 infant deaths.