The adverse effects of utilizing altitude-inappropriate fetal growth curves.

Some newborn nurseries located near sea level are utilizing the Denver (high altitude) fetal growth curve to identify and screen infants at high risk for hypoglycemia and/or polycythemia: small for gestational age (SGA) and large for gestational age (LGA) infants. It has been shown that this curve may underestimate the number of SGA infants. Neonates at high risk for these conditions may therefore go undetected and unscreened. To investigate this possibility, we evaluated the risk for hypoglycemia and polycythemia in 354 newborn infants, comparing a high altitude with a sea level fetal growth curve. Polycythemia was more common in SGA than in LGA and appropriate for gestational age (AGA) infants. By changing from a high altitude to a sea level curve in our sea level population, we were able to detect several hypoglycemia and/or polycythemic infants that would have been missed. No hypoglycemic LGA infants were missed that would not have been screened for other medical indications. If newborn nursery screening for hypoglycemia and polycythemia is to be performed only in high-risk infants (ie, LGA and SGA), an altitude-appropriate fetal growth curve should be used.