Oxytocin and prolactin responses associated with nipple stimulation contraction stress tests.

Levels of oxytocin in plasma of pregnant women in the third trimester undergoing nipple stimulation-contraction stress tests were found, by parametric (paired t test) statistical analysis to be elevated. No differences in the plasma increases in oxytocin levels were found between those patients undergoing successful and those undergoing unsuccessful nipple stimulation-contraction stress tests. No significant differences in plasma levels of prolactin were associated with nipple stimulation in these patients.