Prior T, Paramasivam G, Bennett P, Kumar S
Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, London, UK.
Institute for Reproductive and Developmental Biology, Imperial College London, London, UK.
Ultrasound Obstet Gynecol. 2015 Oct;46(4):460-4. doi: 10.1002/uog.14758.
The true growth potential of a fetus is difficult to predict but recently a new definition, independent of fetal weight, using cerebroplacental (cerebro-umbilical) ratio (CPR) < 0.6765 multiples of the median (MoM), was reported. We applied this definition to a cohort of low-risk pregnancies recruited prospectively to determine if fetuses with CPR < 0.6765 are at increased risk of developing signs of intrapartum fetal compromise.
Recruitment to this prospective observational study took place between March 2011 and March 2014. All women with low-risk singleton pregnancies at term were eligible. Women with known or suspected placental dysfunction were excluded, as were women with fetuses with an estimated fetal weight < 10(th) centile. All participants underwent ultrasound examination prior to active labor (≤ 4 cm cervical dilatation), during which fetal biometry as well as umbilical artery and fetal middle cerebral artery blood flow were assessed. Following delivery, intrapartum and neonatal outcomes were compared between fetuses that had a CPR < 0.6765 MoM and those that had a CPR ≥ 0.6765 MoM.
In total, 775 women were recruited. Fetuses with CPR < 0.6765 MoM were significantly more likely to require Cesarean delivery because of presumed fetal compromise (P < 0.001). These fetuses were also at increased risk of compromise at any time during labor and were less likely to be delivered vaginally, spontaneously or otherwise, than were those with CPR ≥ 0.6765 MoM. CPR < 0.6765 MoM gave a positive predictive value (PPV) for Cesarean delivery because of presumed fetal compromise of 36.7% and a negative predictive value of 88.7%, with a sensitivity of 18% and a specificity of 95.4%.
Fetuses that failed to achieve their growth potential (defined as CPR < 0.6765 MoM) were at increased risk of intrapartum compromise and were less likely to be delivered vaginally. However, a low negative predictive value was observed for fetal compromise and further studies are required to support the translation of this technique into clinical practice.
胎儿的真正生长潜力难以预测，但最近有报道提出了一种新定义，即使用脑胎盘（脑 - 脐）比率（CPR）<中位数倍数（MoM）的0.6765来定义，该定义与胎儿体重无关。我们将此定义应用于前瞻性招募的低风险妊娠队列，以确定CPR <0.6765的胎儿发生产时胎儿窘迫迹象的风险是否增加。
这项前瞻性观察性研究于2011年3月至2014年3月期间进行。所有足月单胎低风险妊娠的妇女均符合条件。已知或疑似胎盘功能障碍的妇女以及估计胎儿体重<第10百分位数的胎儿的妇女被排除在外。所有参与者在活跃分娩前（宫颈扩张≤4cm）接受超声检查，在此期间评估胎儿生物测量以及脐动脉和胎儿大脑中动脉血流。分娩后，比较CPR <0.6765 MoM的胎儿与CPR≥0.6765 MoM的胎儿的产时和新生儿结局。
总共招募了775名妇女。CPR <0.6765 MoM的胎儿因假定的胎儿窘迫而需要剖宫产的可能性显著更高（P <0.001）。这些胎儿在分娩期间任何时候发生窘迫的风险也增加，并且与CPR≥0.6765 MoM的胎儿相比，经阴道分娩（自然分娩或以其他方式）的可能性更小。CPR <0.6765 MoM对因假定的胎儿窘迫而进行剖宫产的阳性预测值（PPV）为36.7％，阴性预测值为88.7％，敏感性为18％，特异性为95.4％。
未达到其生长潜力（定义为CPR <0.6765 MoM）的胎儿发生产时窘迫的风险增加，且经阴道分娩的可能性较小。然而，观察到胎儿窘迫的阴性预测值较低，需要进一步研究以支持将该技术转化为临床实践。
