传统的产前诊断方法是在妊娠中期通过羊膜腔穿刺获取羊水，从羊水中分离胎儿细胞进行培养，对胎儿的染色体异常进行诊断。近年研究证实在羊水悬液中存在大量游离胎儿核酸，可利用从羊水悬液中提取的游离胎儿DNA和RNA，对胎儿的染色体异常和胎儿发育状况进行诊断和评估。这些发现使利用废弃的羊水悬液获取胎儿遗传物质进行产前诊断成为可能，为研究胎儿发育和病理状态开辟了一条新的途径。作者现将近年的相关研究进行综述如下。

Originally prenatal diagnosis was confined to the diagnosis of chromosome abnormalities by cultured cells in amniotic fluid. In recently, cell-free fetal nucleic acids in the supernatant of amniotic fluid, which is usually discarded, can be used as a sample for prenatal diagnosis and monitor the ongoing development of human fetuses in vivo. Amniotic fluid supernatant is a valuable and widely available but under-utilized biological resource. It opened a new way to insights fetal development and pathology. The review was to summarize the current knowledge on cell-free fetal nucleic acids in amniotic fluid.