THE SIGNIFICANCE OF AN ANTENATAL NUCHAL CORD

这项建议的长期目标是评估人类胎儿产前颈索的潜在短期和长期生理和发育影响。最初资助期的具体目标是确定无症状产前脐带绕颈的存在是否具有临床意义，如果是，则确定在制定管理计划时是否有任何潜在价值的辅助发现。待检验的零假设为：（1）脐带绕颈是宫内生活期间的随机短暂事件;（2）分娩前脐带绕颈的存在不会产生胎儿应激的证据，也不会改变短期或长期的胎儿结局;（3）特定的解剖结构与6个月至5岁之间的持续性或神经发育表现无关;（4）胎儿的生物物理和/或生物化学特征不能预测6个月至5岁之间的神经发育表现。将在妊娠18-22周招募330名携带单胎的低风险孕妇。在妊娠24-26周、30- 32周和36-38周，她们将接受无应激试验、生物物理学检查、速度测定、常规I级超声检查和使用彩色血流多普勒确定脐带位置，并由研究小组的一名成员监测妊娠和分娩的临床过程和结局。.受试者和她的医生将对除形态测量结果外的所有结果设盲，除非其他检查结果表明可能存在胎儿损害。将特别关注针对胎儿窘迫、是否存在胎粪、胎儿心率模式、相对于胎龄的出生体重、出生时脐带绕颈、Apgar评分、羊水红细胞生成素和脐动脉血气指征的临床干预的发生率。婴儿随访将包括出生后第5天的颅内超声检查以及6个月、1岁、2岁和5岁时的形态测量和神经发育评估。有证据表明，在实验动物和人类分娩过程中，脐带缠绕会减少脐带血流量，引起胎心率模式的变化，并可能导致发病率和死亡率。胎儿临产前脐带绕颈的发生率似乎与出生时相同。问题是，产前超声检查中的脐带绕颈是否应该引起临床关注。这项提案将提供数据，回答这个问题。

The long range goal of this proposal is to evaluate the potential short- and long-term physiological and developmental effects of an antenatal nuchal cord in the human fetus. The specific aims for the initial funding period are to determine if the presence of an asymptomatic antenatal nuchal cord has clinical significance and, if so, are any ancillary findings of potential value in formulating a management plan. The null hypotheses to be tested are: (1) the presence of a nuchal cord is a random transient event during intrauterine life; (2) the presence of a nuchal cord prior to labor does not produce evidence of fetal stress or alter either short- or long-term fetal outcome:(3) the specific anatomical arrangement is unrelated to either persistence or neurodevelopmental performance between 6 months and 5 years of age; and (4) biophysical and/or biochemical characteristics of fetuses with antenatal nuchal cords are not predictive of neurodevelopmental performance between 6 months and 5 years of age. Three hundred and thirty low risk pregnant women carrying singletons will be recruited at 18-22 weeks gestation. They will undergo a non- stress test, a biophysical profile, velocimetry, a routine level I ultrasound and determination of cord position using color flow Doppler at 24-26, 30- 32 and 36-38 weeks gestation and the clinical course and outcome of the pregnancy and labor will be monitored by a member of the study team. . Both the subject and her physician will be blinded to all but the morphometric findings unless the other test results suggest that fetal compromise may exist. Specific attention will be directed towards the incidence of clinical intervention for the indication of fetal distress, presence or absence of meconium, the fetal heart rate pattern, birth weight for gestational age, nuchal cord at birth, Apgar scores, amniotic fluid erythropoeitin and umbilical artery blood gasses. Infant follow-up will include an intracranial ultrasound on the fifth day of life and morphometric and neurodevelopmental assessments at 6 months, one, two and five years of age. There is evidence in experimental animals and in the human during labor that cord entanglement decreases umbilical blood flow, produces changes in the fetal heart rate pattern and may result in morbidity and mortality. It also appears t the incidence of nuchal cord prior to labor in the human fetus is equivalent to that found at birth. The question is should the ancillary finding of an antenatal nuchal cord on ultrasound exam be a cause for clinical concern. This proposal will provide data that should answer the question.