Epidemiological differences among birth weight and gestational age subgroups of newborns

For a sample of 16,113 women who received prenatal care from the Guatemalan Social Security Institute Hospital, we described the distribution of birth weight and gestational age subgroups and the association between known epidemiologic risk factors and the odds for 1) an appropriate-weight-for-gestational-age preterm vs. a small-for-gestational-age term infant, 2) a small-for-gestational-age preterm vs. a small-for-gestational-age term infant, and 3) a normal ponderal index vs. a low ponderal index term small-for-gestational-age infant. We found that low maternal income, education, height (3147 cm), prepregnancy weight (347.8 kg), and weight gain during pregnancy (30.72 kg) were associated with a greater odds for birth of a term small-for-gestational-age infant (particularly those with a normal ponderal index) than for the birth of a preterm appropriate-weight-for-gestational-age infant. Conversely, medical and pregnancy-related complications were associated with greater odds for a preterm birth of an appropriate- or a small-for-gestational-age infant. Implications of these findings for interventions and research are discussed.