Moessinger A C, Blanc W A, Marone P A, Polsen D C
Pediatr Res. 1982 Feb;16(2):109-12. doi: 10.1203/00006450-198202000-00006.
Umbilical cord length varies considerably and the factors controlling cord length are unknown. Experiments in rat fetuses indicate that (1) restriction of fetal movements by oligohydramnios leads to short cord. The umbilical cords were significantly shorter in proportion to the duration or time of onset of the oligohydramnios. The mean cord length represented 65% of littermate control values when persistent oligohydramnios was induced on day 15, 71% for day 16 and 78% for day 17 (term day 21). (2) Suppression of fetal movements by curarization from day 18 on leads to short cords, irrespective of amniotic fluid volume. The paralyzed fetuses with polyhydramnios had a mean cord length representing 85% of sham operated controls, and those with oligohydramnios and paralysis had a similar mean cord length, 86% of controls. (3) Extra-uterine pregnancies with the fetuses free in the maternal abdominal cavity, yet attached to their umbilical cords, led to cords measuring 147% of littermate controls. (4) In contrast, when the extra-uterine fetuses were fixed to the uterine horn, close to the placental implantation site, with little or no stretch applied to the cord, the mean cord length was 90% od littermate controls. These results indicate that tensile forces on the cord secondary to fetal movements are important determinants of cord length.
脐带长度差异很大，而控制脐带长度的因素尚不清楚。对大鼠胎儿进行的实验表明：（1）羊水过少限制胎儿活动会导致脐带短小。与羊水过少的持续时间或起始时间相比，脐带明显较短。当在第15天诱发持续性羊水过少时，平均脐带长度占同窝对照值的65%；第16天为71%；第17天（足月为第21天）为78%。（2）从第18天起用箭毒使胎儿活动受抑制会导致脐带短小，而与羊水量无关。羊水过多的麻痹胎儿的平均脐带长度占假手术对照的85%，羊水过少且麻痹的胎儿的平均脐带长度与之相似，为对照的86%。（3）胎儿游离于母体腹腔但仍与脐带相连的宫外妊娠，其脐带长度为同窝对照的147%。（4）相反，当宫外胎儿固定于子宫角，靠近胎盘植入部位，脐带几乎没有或没有受到拉伸时，平均脐带长度为同窝对照的90%。这些结果表明，胎儿活动对脐带产生的张力是脐带长度的重要决定因素。
