With the mature application of assisted reproductive technologies, the incidence of multiple pregnancies has increased dramatically, and complications including premature labor, fetal malformations, preeclampsia, and gestational diabetes have also increased. Perinatal prognosis and fetal survival quality can be improved through fetal reduction. Selective fetal reduction in the first trimester may result in a better prognosis than selective fetal reduction in the second trimester, suggesting that early assessment of pregnancy outcome in early pregnancy will provide a significant improvement in maternal and fetal prognosis.

To explore the relationship of ultrasonographic soft markers in early pregnancy and twin-specific markers with the pregnancy outcome of double chorionic double amniotic sac twins (DCDA) .

Pregnant women and fetuses with DCDA twin pregnancies in early pregnancy (11-13⁺⁶ weeks) attending the Department of Ultrasound Medicine of Longgang District Maternity&Child Healthcare Hospital of Shenzhen City from May 2018 to May 2022 were retrospectively selected for the study. The detection rates of ultrasonographic soft markers and twin-specific markers in DCDA twin pregnancies in early pregnancy and their association with adverse pregnancy outcomes. Ultrasonographic soft markers included thickened nuchal translucency (NT), choroid plexus cyst, nasal bone dysplasia, ventricular punctate strong echo, tricuspid regurgitation, absence or inversion of ductus venosus A wave, intestinal echo enhancement, mild dilatation of the renal pelvis, single umbilical artery and right subclavian artery vagus. Twin-specific markers included differences in twin crown-rump length (CRL), twin NT, and twin umbilical cord insertion (UCI). Adverse pregnancy outcomes included miscarriage, stillbirth, neonatal death, structural abnormalities, and genetic abnormalities, with the addition of positive weight gain (≥25% difference in twin weights) as a specific adverse pregnancy outcome. Logistic regression analysis was used to explore the correlation of ultrasonographic soft markers and twin-specific markers of DCDA twin pregnancies in early pregnancy with adverse fetal pregnancy outcomes.

Finally, 418 cases pregnant women of DCDA twin pregnancies in the first trimester were included, of which 342 cases (81.82%) had normal pregnancy outcomes and 76 cases (18.18%) had adverse pregnancy outcomes. The total detection rate of positive ultrasonographic soft markers in twin pregnancies in the first trimester was 10.53% (53/418) ; a total of 61 ultrasonographic soft markers were detected in 53 fetuses with positive ultrasonographic soft markers, and the top three detection rates were NT thickening in 6.94% (29/418), choroid plexus cyst in 2.39% (10/418) and nasal bone dysplasia in 1.67% (7/418). The incidence rate of adverse pregnancy outcomes for fetuses with positive ultrasonographic soft markers was 30.19% (16/53), and the incidence rate of adverse pregnancy outcomes for fetuses with negative ultrasonographic soft markers was 16.44% (60/365) ; the incidence rate of adverse pregnancy outcomes for fetuses with positive ultrasonographic soft markers in the first trimester was higher than fetuses with negative ultrasonographic soft markers (χ²=5.882, P=0.015). Binary Logistic regression analysis results showed that a twin CRL difference≥15% was a risk factor for adverse pregnancy outcomes in twin pregnancy (OR=9.955, 95%CI=1.882-52.662, P=0.007), and a positive twin UCI difference was a risk factor for positive fetal weight in twin pregnancy (OR=3.733, 95%CI=1.300-10.720, P=0.014). The total detection rate of positive twin-specific markers in fetuses with twin pregnancies in early pregnancy was 27.27% (114/418), including 12 cases with a twin CRL difference≥15% and a negative twin UCI difference, 100 cases with a twin CRL difference<15% and a positive twin UCI difference, and 2 cases with a twin CRL difference≥15% and a positive twin UCI difference. The total detection rate of fetuses with ultrasonographic soft markers but positive twin-specific markers in early pregnancy was 25.12% (105/418). The incidence of adverse pregnancy outcomes and positive weight gain among fetuses with negative ultrasound soft markers but positive twin-specific markers was 27.6% (29/105), and the incidence of adverse pregnancy outcomes among fetuses with negative ultrasound soft markers alone was 16.4% (60/365). The incidence of adverse pregnancy outcomes and positive weight gain in fetuses with negative ultrasonographic soft markers but positive twin-specific markers in early pregnancy was higher than the incidence of adverse pregnancy outcomes in fetuses with negative ultrasonographic soft markers alone (χ²=6.641, P=0.010). The total detection rate of positive ultrasonographic soft markers combined with positive twin-specific markers in fetuses with twin pregnancies in early pregnancy was 2.15% (9/418), and the incidence of adverse pregnancy outcomes combined with positive weight gain in fetuses with positive ultrasonographic soft markers combined with positive twin-specific markers was 44.4% (4/9), and the incidence of adverse pregnancy outcomes in fetuses with positive ultrasonographic soft markers alone was 30.2% (16/53). There was no statistically significant difference in the incidence of adverse pregnancy outcomes combined with positive weight gain in fetuses with positive ultrasonographic soft markers combined with positive twin-specific markers compared with the incidence of adverse pregnancy outcomes in fetuses with positive ultrasonographic soft markers alone (χ²=0.212, P=0.645). The results of multivariate Logistic regression analysis showed that NT thickening (OR=2.576, 95%CI=1.146-5.791, P=0.022), twin-fetal CRL difference≥15% (OR=13.167, 95%CI=3.595-48.229, P<0.001), and positive twin-fetal UCI difference (OR=2.369, 95%CI=1.049-5.348, P=0.038) were risk factors for adverse fetal pregnancy outcome and positive weight gain in DCDA twin pregnancies in early pregnancy.

NT thickening, twin-fetal CRL difference≥15%, and positive twin-fetal UCI difference may be risk factors for adverse fetal pregnancy outcomes and positive weight gain in DCDA twin pregnancies in early pregnancy. The fetus with positive ultrasonographic soft markers or positive twin-specific markers should be vigilant, and comprehensive evaluation and close follow-up should be carried out.

随着辅助生殖技术的成熟应用，多胎妊娠的发生率急剧增加，包括早产、胎儿畸形、先兆子痫和妊娠期糖尿病等并发症也随着增多。通过减胎手段可以改善围生期预后及胎儿存活质量，妊娠早期选择性减胎可能会比妊娠中期选择性减胎的预后更佳，提示孕早期尽早评估妊娠结局将改善孕妇及胎儿的预后。

探讨孕早期超声软指标及双胎特有指标与双绒毛膜双羊膜囊（DCDA）双胎妊娠结局之间的关系。

回顾性选取2018年5月—2022年5月在深圳市龙岗区妇幼保健院超声医学科就诊的孕早期（11~13⁺⁶周）DCDA双胎妊娠孕妇及胎儿为研究对象。分析孕早期DCDA双胎妊娠胎儿超声软指标和双胎特有指标的检出率及其与不良妊娠结局的关系。超声软指标包括：颈后透明层（NT）增厚、脉络丛囊肿、鼻骨发育不良、心室点状强回声、右房室瓣反流、静脉导管a波缺失或倒置、肠管回声增强、肾盂轻度扩张、单脐动脉、右锁骨下动脉迷走。双胎特有指标包括：双胎头臀长（CRL）差异、双胎NT差异、双胎脐带插入（UCI）差异。不良妊娠结局包括：流产、死胎、新生儿死亡、结构异常、遗传学异常，另增加体质量阳性（双胎体质量差异≥25%）作为一种特殊的不良妊娠结局。采用Logistic回归分析探讨孕早期DCDA双胎妊娠胎儿超声软指标及双胎特有指标与胎儿不良妊娠结局的相关性。

最终纳入418例孕早期DCDA双胎妊娠胎儿，其中正常妊娠结局342例（81.82%），不良妊娠结局76例（18.18%）。孕早期双胎妊娠胎儿超声软指标阳性的总检出率为10.53%（53/418）；53例超声软指标阳性的胎儿中共检出61个超声软指标，检出率排名前三位的依次为：NT增厚6.94%（29/418），脉络丛囊肿2.39%（10/418）和鼻骨发育不良1.67%（7/418）。超声软指标阳性胎儿不良妊娠结局发生率为30.19%（16/53），高于超声软指标阴性胎儿不良妊娠结局发生率16.44%（60/365）（χ²=5.882，P=0.015）。二元Logistic回归分析结果显示，双胎CRL差异≥15%是双胎妊娠胎儿不良妊娠结局的危险因素（OR=9.955，95%CI=1.882~52.662，P=0.007），双胎UCI差异阳性是双胎妊娠胎儿体质量阳性的危险因素（OR=3.733，95%CI=1.300~10.720，P=0.014）。孕早期双胎妊娠胎儿双胎特有指标阳性的总检出率为27.27%（114/418），包括双胎CRL差异≥15%、双胎UCI差异阴性12例，双胎CRL差异<15%、双胎UCI差异阳性100例，双胎CRL差异≥15%、双胎UCI差异阳性2例。孕早期双胎妊娠胎儿超声软指标阴性但双胎特有指标阳性的总检出率为25.12%（105/418），超声软指标阴性但双胎特有指标阳性胎儿中不良妊娠结局与体质量阳性发生率为27.6%（29/105），单纯超声软指标阴性胎儿中不良妊娠结局发生率为16.4%（60/365）；孕早期超声软指标阴性但双胎特有指标阳性胎儿不良妊娠结局与体质量阳性发生率高于单纯超声软指标阴性胎儿不良妊娠结局发生率（χ²=6.641，P=0.010）。孕早期双胎妊娠胎儿超声软指标阳性合并双胎特有指标阳性的总检出率为2.15%（9/418），超声软指标阳性合并双胎特有指标阳性胎儿中不良妊娠结局并体质量阳性发生率为44.4%（4/9），单纯软指标阳性胎儿中不良妊娠结局发生率为30.2%（16/53），差异无统计学意义（χ²=0.212，P=0.645）。多因素Logistic回归分析结果显示，NT增厚（OR=2.576，95%CI=1.146~5.791，P=0.022）、双胎CRL差异≥15%（OR=13.167，95%CI=3.595~48.229，P<0.001）、双胎UCI差异阳性（OR=2.369，95%CI=1.049~5.348，P=0.038）是孕早期DCDA双胎妊娠胎儿不良妊娠结局与体质量阳性的危险因素。

NT增厚、双胎CRL差异≥15%、双胎UCI差异阳性可能是孕早期DCDA双胎妊娠胎儿不良妊娠结局与体质量阳性的危险因素。对于超声软指标阳性或双胎特有指标阳性的胎儿应提高警惕，需对其进行全面综合评估并密切随访。