Soernes T, Bakke T
Department of Gynecology and Obstetrics, Akershus Central Hospital, Norway.
Am J Obstet Gynecol. 1987 Nov;157(5):1229-30. doi: 10.1016/s0002-9378(87)80299-5.
A current hypothesis on the linear growth of the umbilical cord states that cord length is a function of fetal intrauterine motor activity. If there is some type of intrauterine constraint, the tensile forces on the cord will be diminished, and cord length at term will be shorter than if no such constraint is present. One would expect that the voluntary movements of twins would develop under a constraint and that they would have less free space to move compared with single fetuses. If this hypothesis is valid, cord lengths of twins at term would be shorter than those of single pregnancy infants. We measured the cord lengths of 118 infants in 59 twin births and compared them with cord lengths in 9601 single pregnancies. We found that on the average, the umbilical cord length of the twins was 7.90 cm shorter than that of single pregnancy infants.
目前关于脐带线性生长的一种假说认为，脐带长度是胎儿宫内运动活动的一个函数。如果存在某种类型的宫内限制，脐带上的拉力就会减小，足月时的脐带长度将比不存在这种限制时更短。可以预期，双胞胎的自主运动会在受限的情况下发展，并且与单胎胎儿相比，他们的活动空间会更小。如果这个假说是正确的，足月双胞胎的脐带长度将比单胎妊娠婴儿的脐带长度短。我们测量了59对双胞胎出生的118名婴儿的脐带长度，并将其与9601名单胎妊娠的脐带长度进行了比较。我们发现，双胞胎的脐带平均长度比单胎妊娠婴儿的脐带长度短7.90厘米。
