Mexican Americans' intrauterine growth retardation and maternal risk factors.

This study was designed to evaluate the prevalence of intrauterine growth retardation (IUGR) in Mexican Americans compared to non-Hispanic whites in Arizona. Data were compiled from birth certificates documenting live births in 1986 and 1987. A total of 25,289 Mexican-American and 71,139 white newborns were classified by IUGR. Two methods of IUGR classification were used: the fetal growth ratio (FGR) and the 10th percentile of birthweight by gestational age. A reference growth-distribution data set from the state of California was used to determine IUGR vs non-IUGR newborns. Maternal risk factors were also used to compare IUGR and non-IUGR samples. Overall, Mexican Americans had a lower risk (OR: 0.91) for IUGR than did whites, after controlling for maternal risk factors. Regardless of the IUGR classification method used, more than 88% of IUGR infants were born at term, and more than 60% of IUGR infants had birthweights equal to or greater than 2500 g. Maternal risk factors significantly discriminated between IUGR and non-IUGR infants. Finally, after controlling for maternal risk factors, US-born Mexican mothers were 1.21 times more likely to have an IUGR infant than were Mexico-born mothers. The problem of IUGR and its determinants in Mexican Americans deserves attention in clinical settings.