Salomon L J, Cavicchioni O, Bernard J P, Duyme M, Ville Y
Service de Gynécologie-Obstétrique, Centre Hospitalier Intercommunal de Poissy-St Germain, Poissy, France.
Ultrasound Obstet Gynecol. 2005 Oct;26(5):512-6. doi: 10.1002/uog.1966.
The prevalence and significance of intertwin growth discrepancy in the first trimester of pregnancy are controversial. The aim of this study was to refine the incidence and outcome of this discrepancy in relation to dating of the pregnancy and other biometric parameters.
This prospective study of twin pregnancies initially evaluated at 11-14 weeks' gestation was conducted between 2001 and 2004. Differences in crown-rump length (CRL) and estimated gestational age (GA) were calculated for each twin pair and their distribution was analyzed according to chorionicity and mode of conception (spontaneous or following assisted reproductive technologies). CRL-based GA and actual GA were compared. Other biometric parameters were also compared for each twin pair. The distribution of discrepancies was analyzed according to pregnancy outcome.
A total of 182 twin pregnancies was included. The mean+/-SD discrepancy in CRL was 3.4+/-3.18 mm or 5.1+/-4.69% and the 95th centile was 9.8 mm or 14.3%. There was no influence of chorionicity (P=0.44), mode of conception (P=0.18) and no relation with outcome (P=0.54). In conceptions resulting from assisted technology, the measured CRL of the smaller twin was closer to the actual GA. Cephalic and abdominal biometric measurements were significantly greater in the twin with the smaller CRL (P<0.05). The two cases with a discrepancy>15 mm were affected by trisomy 18 and triploidy, respectively.
CRL discrepancy in twin pregnancies in the first trimester is a frequent finding. Discrepancy>95th centile indicates major growth delay of one twin, which could indicate the presence of aneuploidy. For milder degrees of discordance the CRL of the smaller fetus is a more accurate estimate of the actual GA.
孕早期双胎间生长差异的发生率及意义存在争议。本研究的目的是明确这种差异与孕周及其他生物测量参数相关的发生率和结局。
本前瞻性研究纳入了2001年至2004年间最初在孕11 - 14周进行评估的双胎妊娠。计算每对双胎的顶臀长（CRL）差异和估计孕周（GA），并根据绒毛膜性和受孕方式（自然受孕或辅助生殖技术后受孕）分析其分布情况。比较基于CRL的GA和实际GA。还比较了每对双胎的其他生物测量参数。根据妊娠结局分析差异的分布情况。
共纳入182例双胎妊娠。CRL的平均±标准差差异为3.4±3.18 mm或5.1±4.69%，第95百分位数为9.8 mm或14.3%。绒毛膜性（P = 0.44）、受孕方式（P = 0.18）对其无影响，且与结局无关（P = 0.54）。在辅助技术受孕的妊娠中，较小双胎的测量CRL更接近实际GA。CRL较小的双胎的头围和腹围生物测量值显著更大（P < 0.05）。差异>15 mm的两例分别受18三体和三倍体影响。
孕早期双胎妊娠的CRL差异很常见。差异>第95百分位数表明一个双胎存在严重生长延迟，这可能提示非整倍体的存在。对于程度较轻的不一致情况，较小胎儿的CRL是实际GA的更准确估计。
