THE SIGNIFICANCE OF AN ANTENATAL NUCHAL CORD

这项建议的长期目标是评估产前脐带在人类胎儿中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的产前脐带是否具有临床意义，如果有，是否有任何对制定管理计划有潜在价值的辅助发现。有待检验的无效假设是：(1)脐带绕颈的存在是宫内生命中的随机瞬时事件；(2)分娩前脐带绕颈的存在不会产生胎儿应激的证据，也不会改变胎儿的短期或长期结局：(3)特定的解剖安排与6个月至5岁之间的持续性或神经发育表现无关；(4)产前脐带胎儿的生物物理和/或生化特征不能预测6个月至5岁的神经发育表现。330名怀孕18-22周的低风险单身孕妇将被招募。他们将在妊娠24-26周、30-32周和36-38周接受无负荷测试、生物物理检查、速度测量、常规I级超声和彩色血流多普勒测定脐带位置，研究小组的一名成员将监测妊娠和分娩的临床过程和结局。。受试者和她的医生都将对除了形态测量结果之外的所有结果视而不见，除非其他测试结果表明可能存在胎儿损害。将特别注意胎儿窘迫、有无胎粪、胎儿心率模式、胎龄出生体重、出生时脐带、Apgar评分、羊水促红细胞生成素和脐动脉血气等临床干预的发生率。婴儿的随访将包括在出生第五天进行颅内超声波检查，以及在6个月、1岁、2岁和5岁时进行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，脐带缠绕会减少脐血流量，导致胎儿心率模式的变化，并可能导致发病率和死亡率。人类胎儿临产前脐带绕颈的发生率似乎与出生时相同。问题是，产前超声检查中发现的辅助发现的脐带是否应该引起临床的关注。这项提案将提供应该回答这个问题的数据。

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.