Demographic models of birth outcomes and infant mortality: An alternative measurement approach

Most demographic studies use 2,500 grams of birth weight and 37 weeks of ge station as cutpoints for evaluating the effects of adverse birth outcomes o n infant mortality. We propose an alternative strategy, which relies on con tinuous measures of birth outcomes, identifies an optimal combination of bi rth weight and gestational age for infant survival, and estimates the effec ts of adverse birth outcomes in terms of their departure form this "optimal point". We illustrate the advantages of this approach by estimating a logi stic model using data from the 1989-1991 NCHS linked birth/infant death fil es. Finally, we discuss future applications and methodological issues to be resolved in subsequent research.