孕妇年龄、孕周及体重指数对孕妇外周血中胎儿游离DNA比例的影响 [中文引用][英文引用]

目的 无创产前诊断（noninvasive prenatal testing, NIPT）是通过提取母体外周血中游离DNA，经高通量测序技术和生物信息学分析，发现游离DNA中是否存在比例异常的染色体，进而判断胎儿是否存在染色体非整倍体。孕妇外周血中胎儿游离DNA比例是影响NIPT准确性的重要因素，评价孕妇年龄、孕周和体重指数（body mass index, BMI）对胎儿游离DNA比例的影响对提高NIPT的准确性有重要意义。方法 回顾性分析了2015年3月至2016年5月苏州市立医院2563例孕有正常男性胎儿孕妇的NIPT检测结果及相关数据，提取孕妇外周血胎儿游离DNA浓度、孕妇年龄、孕周和体重指数等信息，对以上参数进行了归一化处理后再进行相关性分析，挖掘孕妇年龄、孕周和BMI对孕妇外周血中胎儿游离DNA比例的影响。结果 数据显示孕妇外周血中胎儿游离DNA比例与孕周呈正相关（线性回归方程y=0.003x+0.060，R²=0.752，P=0.01144）；孕妇年龄与BMI也呈正相关（线性回归方程y=0.112x+18.80，R²=0.721，P=6.46E-08）；而胎儿游离DNA比例与孕妇BMI、年龄均呈负相关，且在样本量较大时相关性显著。结论 孕妇年龄、BMI的增加都会相对降低孕妇外周血中胎儿游离DNA的比例，孕妇年龄越大则BMI也会相对越大，而孕周的增大会提高孕妇外周血中胎儿游离DNA比例，因此，针对高龄且高BMI值的孕妇适当延后进行NIPT的孕周可以提高NIPT检测的准确性。

Objective Noninvasive prenatal testing is a new technology based on the fact that fetal DNA has been found in maternal plasma. Therefore, by extracting cell-free DNA from maternal plasma with then high through sequencing and bioinfmatic analysis, screening of fetal aneuploidy become reality. However, the fraction of circulating cell-free fetal DNA in maternal plasma is an essential factor which affect accuracy of Noninvasive prenatal testing, therefore, to evaluate the factors which relate to fraction of circulating cell-free fetal DNA in maternal plasma, such as maternal age, gestational age and body mass index , could improve the accuracy of Noninvasive prenatal testing. Method 2563 male pregnancies that received Noninvasive prenatal testing at Center for Reproduction and Genetics of Nanjing Medical University Affiliated Suzhou Hospital from March, 2015 to May, 2016 were involved in this study, and the relationship between maternal age, gestational age, body mass index and fraction of circulating cell-free fetal DNA in maternal plasma were performed normalization and then analysed by correlation analysis. Results The pregnant woman aged about 27 and account mostly in this study and the average gestational age was 17~18 weeks. The peak of body mass index and fraction of circulating cell-free fetal DNA in maternal plasma were 22 kg/m² and 0.12, respectively. The correlation analysis showed positive correlation between gestational age and fraction of circulating cell-free fetal DNA in maternal plasma (Linear equation of regression: y=0.003x+0.060，R²=0.752，P=0.01144), and displayed negative correlation between maternal age, BMI and fraction of circulating cell-free fetal DNA in maternal plasma, the maternal age and body mass index also displayed positive correlation (Linear equation of regression: y=0.112x+18.80，R²=0.721，P=6.46E-08). Conclusions The fraction of circulating cell-free fetal DNA in maternal plasma showed reserved trend of maternal age and body mass index, but displayed same trend with gestational age, and maternal age and body mass index showed negative correlation. Therefore, appropriate gestational age of Noninvasive prenatal testing should be given for those pregnancies had advanced maternal age and higher body mass index.