Oxytocin challenge test results compared with simultaneously studied serum human placental lactogen and free estriol levels in high-risk pregnant women.
Three perinatal health indicators (serum human placental lactogen [hPL] levels, serum free estriol [E3] levels, and OCT) were simultaneously completed in 149 high-risk women who were more than 34 weeks pregnant. There was a significant correlation between the hPL and E3 results (r = 0.28, p less than 0.01). There was a 15.4% positive OCT result rate and the blood hormone values for the negative and positive OCT groups were compared. There was a significantly lower hPL value in the positive OCT group (4.7 +/- S.E.M. 0.4 vs. 6.2 +/- S.E.M. 0.2 micrograms/ml for positive and negative groups, respectively), whereas the free E3 levels were not different in these two OCT groups (14.8 +/- S.E.M. 1.5 vs. 16.3 +/- S.E.M. 0.7 ng/ml for positive and negative groups, respectively). The free E3 value did not help in predicting the OCT result as the low free E3 subgroup had the same frequency of positive OCT result as did the over-all group. There was a highly significant increase in the positive OCT results (42.9%) in women with a low hPL value (p less than 0.01). In those women with an hPL value of 6.0 microgram/ml or more there were only 8% positive OCT's. It is concluded that on hPL test at about 34 weeks of gestation could be used to screen pregnant women, and if the value were low (less than 4.0 microgram/ml) an OCT evaluation test would be indicated, for there is a very high frequency of positive results in that subgroup of women.