Oxytocinase and human placental lactogen for the prediction of intrauterine growth retardation.

Oxytocinase and human placental lactogen (hPL) were measured in 705 serial maternal plasma samples collected from 74 patients whose pregnancies were complicated by hypertension. The trend and absolute levels of each substance were evaluated in a search for reliable antepartum indicators of intrauterine growth retardation (IUGR). There were 21 patients who were delivered of growth-retarded infants and the oxytocinase values were abnormal in 16 cases (75 per cent), while hPL levels were abnormal in 15 cases (71 per cent). There were 24 patients with subnormal placental weights. Abnormal oxytocinase values were observed in 17 (71 per cent) and abnormal hPL in 19 cases (79 per cent). The remaining 37 patients had "normal" fetal and placental weights. Abnormal oxytocinase values were observed in 15 patients (41 per cent) and abnormal hPL in 19 (52 per cent). In this group of pregnant mothers thought to be at risk for IUGR due to pregnancy hypertension, either test alone predicted subnormal neonatal or placental weight in about three fourths of cases. However, in the mothers with hypertension, who had no evidence of IUGR, false abnormal values of oxytocinase and hPL were found in nearly half the patients. No advantage was gained in the predictive accuracy when both tests were used.