Hagelin A, Leyon J
Department of Obstetrics and Gynecology, Kärnsjukhuset, Skövde, Sweden.
Acta Obstet Gynecol Scand. 1998 Sep;77(8):841-4.
There has been some controversy regarding the effect that a long labor can have on fetal well-being. This study was undertaken to evaluate the effect of duration of labor both the first and second stage on the acid-base variables in the umbilical artery of the newborn.
Bloodsampling was attempted from all infants born at our department between October 1994 and September 1995. Nineteen hundred and forty-one live infants were delivered during the period. Sampling was unsuccessful in 264 cases and after excluding infants with operative delivery, multiple gestations, breech presentation, prematurity, postmaturity and infants small for gestational age 1255 remained singleton, term infants with vertex presentation and non-operative vaginal birth.
We found no correlation between duration of the first stage of labor and neither pH nor base excess in umbilical artery blood. There was a significant correlation between duration of the second stage of labor and both the pH and base excess. For vaginal nulliparas we found that pH=7.30-0.016 x second stage duration in hours and base excess=-3.71-0.692 x second stage duration in hours. For women with previous vaginal births pH=7.31-0.029 x second stage duration in hours and base excess=-2.38-1.306 x second stage duration in hours.
We find no correlation between duration of the first stage of labor and umbilical artery pH or base excess. We do find a correlation between duration of the second stage of labor and the umbilical artery pH and base excess. However, a prolongation of the second stage with as much as three hours would give an expected lowering of the umbilical artery pH with only 0.05 and of base excess with 2.1 mmol/l for vaginal nulliparas and correspondingly with 0.09 and 3.9 mmol/l in women with previous vaginal births. This effect on pH and base excess is so small that it is hardly clinically relevant and we do not find any support for the belief that a long labor -- in the absence of other risk factors -- is to the disadvantage of the fetus.
关于产程延长对胎儿健康的影响一直存在一些争议。本研究旨在评估第一产程和第二产程的时长对新生儿脐动脉酸碱变量的影响。
对1994年10月至1995年9月在我科出生的所有婴儿尝试进行血样采集。在此期间共分娩1941例活婴。264例采样未成功，排除手术分娩、多胎妊娠、臀位、早产、过期产以及小于胎龄儿后，1255例仍为单胎、足月、头位且经阴道非手术分娩的婴儿。
我们发现第一产程时长与脐动脉血的pH值及碱剩余均无相关性。第二产程时长与pH值和碱剩余均存在显著相关性。对于初产妇，我们发现pH值 = 7.30 - 0.016×第二产程时长（小时），碱剩余 = -3.71 - 0.692×第二产程时长（小时）。对于有过阴道分娩史的女性，pH值 = 7.31 - 0.029×第二产程时长（小时），碱剩余 = -2.38 - 1.306×第二产程时长（小时）。
我们发现第一产程时长与脐动脉pH值或碱剩余无相关性。我们确实发现第二产程时长与脐动脉pH值和碱剩余存在相关性。然而，对于初产妇，第二产程延长多达3小时预计只会使脐动脉pH值降低0.05，碱剩余降低2.1 mmol/L；对于有过阴道分娩史的女性，相应地pH值降低0.09，碱剩余降低3.9 mmol/L。这种对pH值和碱剩余的影响非常小，几乎没有临床相关性，并且我们没有找到任何证据支持在没有其他危险因素的情况下产程延长对胎儿不利这一观点。
