Studies of maternal plasma renin concentration (PRC) and plasma renin activity (PRA) and cord venous PRC and PRA in the primigravidae delivered under lumbar epidural analgesia.

In order to find out whether epidural analgesia, significantly altered the maternal and cord venous Plasma Renin Concentration (PRC) and Plasma Renin Activity (PRA) in the primiparae, a radioimmunoassay measurement of these renin components was carried out on 40 maternal plasma and 18 cord venous plasma samples. The subjects were 20 primiparae who had uneventful antenatal course, 10 of whom were delivered under epidural analgesia, while others (control group) (n = 10) had routine narcotic analgesia in labour. Maternal venous blood samples were taken in the lateral recumbent position at induction of labour, and immediately after delivery, while the cord venous blood samples were obtained just before or immediately after expulsion of the placenta. The mean +/- SEN of maternal pre-induction PRC and PRA, in the control group were 5.56 +/- 0.32 and 3.81 +/- 0.17 nmgl-1hr-1; while the corresponding immediate post delivery values were 5.05 +/- 0.35 and 2.33 +/- 0.06 respectively. In the epidural analgesia group, the mean maternal pre-induction and immediate post-delivery PRC and PRA values were 5.68 +/- 0.22; 3.49 +/- 0.2; and 5.05 +/- 0.35 and 2.36 +/- 0.06 ngml-1hr-1 respectively. The mean cord venous plasma PRC and PRA in the control group were 3.22 +/- 0.17 and 1.18 +/- 0.03 respectively while the corresponding PRC and PRA values for the epidural analgesia group were 2.93 +/- 0.20, and 1.24 +/- 0.04 ngml-1hr-1 respectively.(ABSTRACT TRUNCATED AT 250 WORDS)