孕妇体位变换对母儿循环的影响

Invesugation of fetal circulation in relation to varionus maternal body positions

随意抽样正常妊娠２７～４０周孕妇５０例。仰卧位１５分钟后改为左侧卧位。用脉冲多普勒诊断装置分别测定其右侧子宫动脉（ＵｔＡ）、脐动脉（ＵＡ）、胎儿腹主动脉（ＤＡ）的血流速波形，并从连续且稳定的五个血流速波形计算血管阻力指数（ＲＩ），按２７～３２周，３３～３４周，３５～３６周、３７～３８周，３９～４０周分为五组，进行统计学分析。结果如下：（１）妊娠周数与ＵＡ－ＲＩ间呈负相关关系（ｒ＝４０４４，Ｐ＜０．０５）；（２）妊娠３７周后，孕妇体位变换引起ＵｔＡ－ＲＩ、ＵＡ－ＲＩ明显降低；（３）左侧卧位时，ＵｔＡ－ＲＩ与ＵＡ－ＲＩ间明显相关（ｒ＝０．４００８，Ｐ＜０．０５）；（４）左侧卧位的ＤＡ－ＲＩ值较仰卧位时低，但差异无显著性。提示：妊娠后期，孕妇体位变换对母儿循环有影响，取左侧卧位有利于胎儿发育。

o determine the possible effect of various maternalbody position on feto-maternal circulation, we per-formed Doppler examinations on 50 women at differentstages between the 27th and 40th week of normal preg-nancy, Flow velocity waveforms of the umbilical artery,fetal descending aorta, and maternal uterine artery wererecorded by pulsed Doppler scanner equipped with3.5MHz transducer(ALOKA SSD 680).The reeis-tance index (RI)was calculated with the patient lyinginitially in the supine position,then 15 minutes later, inthe lateral recumbent position. Maternal blood pressure,placental site, and fetal position were also assessed forpossible relationship with the maternal position reflectedby the resistance indices.The following results were obtained:(1) a nega-tive correlation was observed between gestational periodand umbilical artery flow velocity(r=0.404,P<0.05).(2)although up to the 37th week no outstand-ing difference was noted in the effect of maternal posi-tion on the flow velocitv of the uterine and umbilicalartery, from weeh 37 to 40,the resistance indicesrecorded in the supine position were significantly higherthan those associated with the lateral recumbent posi-tion(P<0.05). In the lateral recumbent position.Flow velocity of the umbilical artery was consistantly indose correlation with that of the uterine artery. Howev-er maternal position had no bearing on the flow velocityin the fetal descending aorta;(3) no significant relation-ship was indicated between the flow velocity of the um-bilical artery and blood pressure,placental site or fetalposition.These results suggested that after the 37th week of pregnancy the supine position of the gravida may haveadverse effects on the feto-maternal circulation.As aprecautionary measure in maintaining a favorable stateof feto-maternal circulation, pregnant women aretherefore advised to avoid lying on their back from aboutthe 37th week to fine of delivery.