[Fetal circulation in relation to various maternal body positions]

To determine the possible effect of various maternal body position on feto-maternal circulation, we performed Doppler examinations on 50 women at different stages between the 27th and 40th week of normal pregnancy. Flow velocity waveforms of the umbilical artery, fetal descending aorta, and maternal uterine artery were recorded by pulsed Doppler scanner equipped with a 3.5MHz transducer (ALOKA SSD 680). The resistance index (RI) was calculated with the patient lying initially in the supine position, then 15 minutes later, in the lateral recumbent position. Maternal blood pressure, placental site, and fetal position were also assessed for possible relationship with the maternal position reflected by the resistance indices. The following results were obtained: (1) a negative correlation was observed between gestational period and umbilical artery flow velocity (r = -0.404, P < 0.05). (2) although up to the 37th week no outstanding difference was noted in the effect of maternal position on the flow velocity of the uterine and umbilical artery, from weeks 37 to 40, the resistance indices recorded in the supine position were significantly higher than those associated with the lateral recumbent position (P < 0.05). In the lateral recumbent position. Flow velocity of the umbilical artery was consistently in close correlation with that of the uterine artery. However maternal position had no bearing on the flow velocity in the fetal descending aorta; (3) no significant relationship was indicated between the flow velocity of the umbilical artery and blood pressure, placental site or fetal position.(ABSTRACT TRUNCATED AT 250 WORDS)