Causes of intrauterine growth restriction.

IUGR is a relatively common problem and a potential cause of significant perinatal morbidity and mortality. There are many possible causes of IUGR, and some cases may involve more than one (Table 1). Although an underlying cause may not always be identifiable, it it important to consider all of these factors because identification of the underlying cause of the IUGR may impact short-term management as well as long-term prognosis. The cornerstone of management for IUGR involves close antenatal surveillance with a well-timed delivery. Antenatal testing in the form of fetal heart rate monitoring, ultrasonographic evaluation, and, on occasion, umbilical blood sampling allows for ongoing surveillance of the growth-retarded fetus. Intrapartum management should include close fetal heart rate monitoring because the ability of the growth-restricted fetus to tolerate labor generally is low and the risk for acidosis is high. A pediatric team should attend the delivery because the risk of meconium aspiration and the frequency of low Apgar scores and metabolic disorders are high. The biochemical mediators reviewed in this article are not likely to be independent causative factors in IUGR; it is more likely they are important mediators of a pathologic process set in motion by other agents or insults. A better understanding of how these mediators contribute to the pathophysiology of IUGR will improve our understanding of this disorder and may allow for therapeutic interventions in the underlying pathophysiologic process.