Urinary estrogens in postterm pregnancy.

A 40-month retrospective review of 677 postterm pregnancies was undertaken to determine the usefulness of 24-hour urinary estrogen per gram of creatinine (E/Cr) in monitoring such pregnancies. The cutoff value between normal and low E/Cr values was chosen at the tenth percentile (18 mg/gm). The corrected perinatal mortality rate (PMR) in post-term pregnancies with normal E/Cr was 0.23% (1/426) and was not different from that at term (0.23%; 4/1,775). However, in post-term pregnancies with low E/Cr, the corrected PMR was 9.2% (4/43), representing a 40-fold increase (P less than 0.001). The incidence of fetal distress was also significantly higher in patients with low E/Cr (57%) than in those with normal E/Cr (5.5%; P less than 0.001). It was worrisome to note that three of four stillborn infants had antepartum fetal heart testing within 4 days, which indicated fetal well-being. The E/Cr appears to be a reliable test for identifying those postterm pregnancies at risk that might benefit from obstetric intervention.