双胎妊娠染色体异常的产前筛查及产前诊断

双胎妊娠发生胎儿畸形、染色体异常的风险较单胎妊娠高。近年来双胎妊娠发生率和高龄产妇数量不断增加，双胎妊娠的早期筛查以及产前诊断十分重要。早孕期，颈项透明层(nuchal translucency，NT)超声筛查是重要手段，不建议单独使用血清学筛查；中孕期超声结构筛查对检出胎儿结构异常有一定意义。无创产前基因检测技术的发展，对降低侵入性产前诊断的风险有重要意义，但由于目前临床证据尚不充分，双胎妊娠行无创基因检测仍需谨慎。

Prenatal screening and prenatal diagnosis of chromosomal abnormalities in twin pregnancy

The risk of fetal malformation and chromosomal abnormalities in twin pregnancy is higher than that in single pregnancy. In recent years, the incidence of twin pregnancies and the number of pregnant women with advanced age are increasing, which makes the prenatal screening and prenatal diagnosis to be very important. In first trimester, nuchal translucency (NT) ultrasound screening is an important means, and serological screening alone is not recommended. In second trimester, ultrasound structure screening has certain significance for detecting fetal structural abnormalities. With the development of non-invasive prenatal genetic testing technology, it is of great significance in reducing the risk of invasive prenatal diagnosis. However, due to the current lack of clinical evidence, non-invasive genetic testing for twin pregnancy still requires caution.