Optimal growth modeling.

Abnormal fetal growth is associated with preterm birth, stillbirth, neonatal death, respiratory distress syndrome, and necrotizing enterocolitis. An optimal fetal growth standard would be one that most correctly identifies the fetus at risk for poor perinatal outcome. A growth standard that is created using population-specific data is more applicable than generalized growth curves since there is evidence that optimal neonatal outcome is achieved at different birth weights in different populations. The development of fetal growth standards based exclusively on neonatal birth weights is flawed as fetal growth restriction is associated with preterm delivery. Likewise, employing clinically derived ultrasound standards for term gestations would include a population that is more likely to have abnormal growth. Novel approaches to defining normal intrauterine growth combine birth weights at term and fetal growth patterns in-utero to create growth curves useful in defining the normal intrauterine growth experience. This review examines the performance of a variety of the growth characterizing standards that have been employed to define abnormal growth and examines their performance in the prediction of adverse perinatal outcome.