Demographics of fetuses
A total of 43,721 pregnancies with low-pass GS and ultrasonography from
29 provinces in China were included in this study (Figure S1). The mean
maternal age was 32.65\(\pm\)6.10 years, and the mean gestational week
(at the time of low-pass GS) was 21.52\(\pm\)4.49 weeks. Aneuploidy
yields were 6.60% (878/13,312) , 7.24% (1,280/17,679), and 2.52%
(321/12,730) of fetuses with ultrasonographic anomalies, soft markers,
and no identifiable anomalies, whereas the pCNV yields were 6.24%
(831/13,312) , 3.64% (644/17,679), and (1.94%, 247/12,730),
respectively (Table 1). The most common aneuploidy in fetuses was
trisomy 21 (3.09%, 1,350/43,721), followed by trisomy 18 (1.11%,
N=486/43,721) and 45,X syndrome (0.52%, 229/43,721), while the most
common pCNV in fetuses was 22q11.21 deletion (0.27%, 119/43,721),
followed by 15q11.2 deletion (0.24%, 105/43,721) and Xp22.31 deletion
(0.22%, 96/43,721).
The yield of aneuploidy in the first trimester of pregnancies with
ultrasonographic anomalies and soft markers was ~9
(333/736 vs 501/10,148) and ~3 times (873/6,583 vs
391/9,775) higher than that in the second trimester, respectively (Table
1). Additionally, The yield of pCNV of each trimester was significantly
higher than control group. There was no obvious trend for the yields
between different trimesters (Table S1).