[Study on blood levels of oxytocin and neurophysins during labor and lactation (author's transl)].

For the study on initiation of labor, a highly sensitive and specific radioimmunoassay for oxytocin (OT) was developed. Investigations were performed on the blood levels of OT and neurophysins in women during labor, lactation as well as in umbilical vessels. The blood was assayed for OT and Estrogen Stimulated Neurophysin (ESN), Nicotine Stimulated Neurophysin (NSN) in each specific radioimmunoassay. The mean value of plasma OT levels of women without labor pains (5 minutes interval) ws 217.3 +/- 36.02 (pg/ml, Mean +/- S.E.) whereas the values at 28 to 40 weeks of gestation was much lower than those. At delivery the OT level in maternal plasma was 176.3 30.92 and 207.5 62.90 in the umbilical vein respectively. There was no statistical difference in the level of OT before and after lactation. ESN level was higher during lactation and NSN level showed the similar pattern. At delivery NSN concentration in the umbilical artery was higher than that in the vein. These data suggest that hypothalamo-pituitary function correlate with labor and lactation.