Factors affecting outcome in post-term birth.

Studies published in the past year confirm that, under current conditions of good ascertainment of gestational age and careful clinical management of post-term pregnancies, post-term births are not at increased risk of perinatal mortality. They are, however, still at increased risk of intrapartum fetal distress and cesarean birth. The main risk factor for poor fetal and neonatal outcomes is small fetal size. Risk markers for those at risk of intrapartum difficulties include amniotic fluid volume and fetal biophysical profile. While there is no longer increased mortality associated with post-term birth per se, this is very much the result of clinical selection factors and modern perinatal management. Post-term pregnancies remain an obstetrical risk group.