Variation in infant birth weight: socioeconomic factors versus medical conditions.

This paper seeks to determine the relative effect of socioeconomic variables and medical conditions in explaining changes in infant birth weight, specifically, low birth weight (LBW). Using ordinary least squares regression, we first analyze the effects of these variables on the birth weight of 621 infants. Four of the independent variables--gestational age in number of days, sex, parity, and health insurance--are statistically significant (P<.05) and explain 64 percent of the variation in infant birth weight. But in a subset of 18 infants born with LBW to mothers < or = 18 years of age or 35 > or = years of age, only gestational age in number of days is statistically significant.