BACKGROUND The rate of twinning continues to increase due to the combined effect of a rise in parental age and increased use of assisted reproductive technology. The risk of congenital anomalies in twins is higher than in singletons, but it is less well reported in relation to growth patterns. We focused to the auxological outcome of twin pregnancies when one or both of twins are affected by one or more malformations. METHODS We conducted a retrospective observational study reviewing the clinical charts of twins admitted in the period between January 2003 and December 2018 at the University Hospital of Palermo. The associations between malformations and anthropometric variables at birth were analyzed by comparison within each twin pair and regarding each variable as ordered difference between the two twins. RESULTS We studied data of 488 neonates (52% females) from 244 pregnancies. The rate of major congenital anomalies was 11%, affecting significantly the smaller twin (p = .00018; Odds ratio 3.21; 95% CI 1.65 6.59). Malformation class distribution was as following: genitourinary (24%), gastrointestinal (20%), cardiovascular (18.5%), musculoskeletal (11%), central nervous system (9%), syndromic (9%), ocular (5.5%) and diaphragmatic hernia (2%). The most predictive value, the Birthweight (BW) difference mean ratio in malformed versus not malformed neonates (- 0.31 vs 0.02; p = .0016) was distributed equally lower than zero in all malformed twins, except for those with congenital heart defects (p = .0000083). Microcephaly (head circumference < 2 standard deviation, SD) was present in 3% of symmetrically smaller twin, and severe microcephaly (< 3 SD) was present in 0.6%. We found that an intertwin BW discordance of 18% or greater identified 50% of neonates with microcephaly, but only 11% of malformed twins. CONCLUSIONS In case of one twin with a BW < 10th centile, a concomitant intertwin BW discordance ≥18% could reveal an increased risk for microcephaly but not for malformation. Lower values of BW, Ponderal index, Body mass index but above all negative value of BW difference mean ratio are associated with malformations in twin pairs.

中文翻译：

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双胞胎先天畸形的生长方式和相关危险因素。

背景技术由于父母年龄的增加和辅助生殖技术的增加使用的结合作用，孪生率继续增加。双胞胎先天性异常的风险高于单胎，但有关生长方式的报道较少。当双胞胎中的一个或两个都受到一个或多个畸形的影响时，我们专注于双胞胎怀孕的生理学结果。方法我们进行了一项回顾性观察性研究，回顾了2003年1月至2018年12月在巴勒莫大学医院收治的双胞胎的临床图表。通过比较每对双胞胎中的出生畸形和人体测量学变量之间的关联，并将每对变量视为两个双胞胎之间的有序差异来进行分析。结果我们研究了来自244例怀孕的488例新生儿（52％的女性）的数据。主要先天畸形的发生率为11％，对较小的双胞胎有显着影响（p = .00018；赔率为3.21； 95％CI为1.65 6.59）。畸形类别分布如下：泌尿生殖系统（24％），胃肠道（20％），心血管（18.5％），肌肉骨骼（11％），中枢神经系统（9％），症状（9％），眼部（5.5％）和diaphragm疝（2％）。最具预测价值的是，畸形新生儿与非畸形新生儿的出生体重（BW）差异平均比（-0.31 vs 0.02； p = .0016）在所有畸形双胞胎中平均分配为低于零，除了那些先天性心脏缺陷的人（p = .0000083）。3％的对称较小双胞胎中存在小头畸形（头围<2标准偏差，SD），严重的小头畸形（< 3 SD）的含量为0.6％。我们发现18％或更高的双胎BW不一致性发现50％的小头畸形新生儿，而畸形的双胞胎只有11％。结论如果一对孪生的BW <10％，则双胞胎BW不一致≥18％可能会增加小头畸形的风险，但不会导致畸形。BW，Ponderal指数，体重指数较低，但BW差均比的所有负值均高于双胞胎畸形。