结论: 在有产前诊断为指征的孕妇, 胎儿染色体异率为6.4%,染色体异常携带者和各种三体为主要的异常,是高龄以及IUGR最常见的异常.Conclusion: During the second and third trimesters, the rate of Chr - abn was 6.4 %....