Since 1979, the Centers for Disease Control and Prevention (CDC) has assisted states to monitor nutritional status during the course of pregnancy. The initial design of the Pregnancy Nutrition Surveillance System (PNSS) monitored nutrition-related problems, including pregravida weight status, low hematology values, smoking behavior and birth outcome, such as birth weight. In 1989, PNSS was enhanced by adding nutrition and behavioral risk factor information as part of the surveillance data. The emphasis of the enhanced PNSS is to better quantify preventable risk behaviors such as smoking and alcohol consumption and to examine the relationship of nutritional and behavioral risks during pregnancy to birth outcome.

The PNSS utilizes data collected from health, nutrition and food assistance programs for pregnant women. Missouri's PNSS data sets include records from low-income women only, and do not represent all pregnant women in the state. In Missouri, the Special Supplemental Nutrition program for Women, Infants and Children (WIC) is the major source of data for PNSS. Work towards a full-scale implementation of the PNSS in Missouri began in 1991. By the end of 1993, all local public health agencies in the state were sending the majority of the required data items for PNSS to CDC.

State and territorial health departments as well as Native American Indian agencies participating in PNSS submit information quarterly to CDC on computer tapes or diskettes. These data are analyzed by CDC annually, and summaries are returned to the Missouri Department of Health and Senior Services (DHSS) for data analysis and use in program planning, management and the evaluation of maternal health programs and activities at the state and local levels. Twenty-three tables are routinely generated by CDC. These tables are summarized by state, region, county and clinic-specific information. Table summaries of national data are also received.