The effect of isoxsuprine treatment of estrogen levels in maternal and umbilical cord plasma.

Estrogen concentrations in maternal plasma were determined in ten apparently normal patients attending clinic in the last trimester of pregnancy before, during, and after a maximum of four weeks isoxsuprine treatment. Eleven control patients were also studied at similar times of pregnancy. Isoxsuprine treatment appeared to have no specific effect on the levels of either estradiol alone or on total estrogens with all patients studied showing some increase in the concentrations of these estrogens as the pregnancies approached term. In four other patients treated with isoxsuprine for pregnancy complications, changes in plasma total estrogen concentrations during treatment were variable and did not correlate with the amount administered. The levels of estradiol in umbilical cord plasma from 17 isoxsuprine-treated pregnancies were similar to those observed in 24 non-treated pregnancies.