Neonatal complications of postterm gestation.

Postterm gestation infants represent about 10% of the newborn population and, as compared to term gestation infants, have an increased incidence of perinatal and neonatal problems. Most postterm infants are normal appearing, although changes in the skin and a loss of subcutaneous fat occur in some. A smaller number experience the onset of fetal wasting late in gestation and appear dysmature (postmature) at birth. The incidence of infants with dysmaturity increases as postterm gestation continues; however, the prevalence of dysmaturity is greater in term infants. The most significant neonatal problems in the postterm gestation infant are the result of fetal distress and perinatal asphyxia. Those infants affected most severely may have hypoxic encephalopathy, seizures and meconium aspiration syndrome. Other problems are birth trauma (due to the large size of some postterm infants) and polycythemia. Anencephaly is associated with postterm gestation. The later intellectual development of postterm gestation infants appears normal except for those with perinatal asphyxia or severe neonatal problems. The long-term somatic growth is normal, even in dysmature-appearing infants. Postterm infants are at increased risk for perinatal asphyxia; however, with careful obstetric management, most neonatal problems can be prevented.