唐氏综合征，也称21-三体，是活产儿中最常见的染色体非整倍体，患儿会出现智力障碍、生长迟缓、多器官畸形等临床表现，需要长期的医疗干预和社会支持，为家庭和社会带来了沉重的心理压力和经济负担。18-三体和13-三体在活产儿染色体非整倍体中发生率仅次于21-三体，位列第二位和第三位。18-三体及13-三体的患儿常表现出广泛的结构异常，通常在出生后数天到数周内死亡。由染色体非整倍体所致的综合征目前尚无法治愈，因此通过有效的筛查及诊断手段防止患儿的出生尤为重要。近几十年间，针对以唐氏综合征为主的染色体非整倍体的产前筛查方法不断发展和更新，目前广泛实施的包括综合超声及血清学标志物的联合筛查，以及近年来新出现的基于母体外周血胎儿游离DNA的无创产前筛查（NIPT）技术。NIPT技术出现后，以其对于染色体非整倍体优越的筛查效能，逐渐成为唐氏综合征一线推荐的筛查方案。血清学筛查在染色非整倍体筛查方面虽不及NIPT，但综合考虑筛查范围、技术操作难度、成本投入等方面，其在出生缺陷筛查中仍有重要的作用。

As the most common chromosomal aneuploidy in newborns，the patients with Down's syndrome，also referred to as trisomy 21，have clinical manifestations such as intellectual disability，growth retardation，and multiple organ malformations，requiring long-term medical intervention and social support，which brings heavy psychological pressure and economic burden to families and society. Trisomy 18 and trisomy 13 were the second and third most common chromosomal aneuploidies in live births after trisomy 21. Infants with trisomies 18 and 13 often present with extensive structural abnormalities and usually die within days to weeks after birth. There is no cure for the syndrome caused by chromosome aneuploidy at present，so it is particularly important to prevent the birth of children through effective screening and diagnosis. In recent decades，prenatal screening methods for chromosomal aneuploidies，with Down's syndrome as the main one，have been developed and updated. At present，the widely implemented screening methods include combined screening of comprehensive ultrasound and serological markers，and NIPT technology which provides cell-free fetal DNA in maternal blood，has emerged in recent years. NIPT has gradually become the first-line recommended screening strategy for Down's syndrome due to its superior screening efficiency for chromosome aneuploidies. Although serological screening is not as good as NIPT in the detection of chromosomal aneuploidies，it still has its important role in the screening for birth defects considering the screening scope，technical difficulty and cost.