Ultrasound assessment of the postmature pregnancy.

The use of ultrasound to identify the fetus at risk for postmaturity among postterm pregnancies was evaluated. The ultrasound findings in 85 postterm pregnancies were reviewed. No grade 0 or grade 1 placentas were observed and grade 2 and 3 placentas were found with similar frequency. The incidence of advanced postmaturity was 12.9%. Advanced postmaturity was found with grade 2 and 3 placentas. Oligohydramnios was very common (81.8%) among pregnancies resulting in postmaturity. The neonatal ponderal index was higher with grade 2 placentas than with grade 3 placentas. The presence of immature placentas (grade 0 or 1) is rare after 42 weeks of gestation. Placental grading cannot be used to predict postmaturity.