Infants in the lowest 7.5 percent of birth weight account for two-thirds of infant deaths. Among the FGR infants that live, there is an increased frequency of hypoglycemia, hypothermia, polycythemia, neurodevelopmental deficits, and cerebral palsy. Later in life the risk of hypertension, cardiovascular disease, and non-insulin dependent diabetes is elevated. Therefore, FGR infants account for a substantial proportion of early death and morbidity and chronic illness. However, most cases of FGR are of unknown cause .
Detection occurs as late as the third trimester, delaying clinical support of the pregnancy.
When the underlying cause is unknown, care may be restricted to careful monitoring, reactive treatment, and early induction of labor. There is an urgent need to understand the underlying bases for idiopathic FGR in order to provide early diagnosis and to suggest prophylactic measures that can be taken to restore the normal growth trajectory of the fetus. FGR has a strong genetic component. Therefore, a search for genetic influences on fetal growth should focus on those molecules that affect the fetal supply of nutrients and growth factors. There are five growth hormone-related genes.