Chinese scientists evaluate the effectiveness of non-invasive prenatal testing for pregnant women older than 35 years

In China, the medical guidelines recommend performing noninvasive prenatal testing (NIPT) with caution for pregnant women aged 35 years or older. However, the Mother and Child Health Care Law suggests that all primiparous women whose age is older than 35 years undergo prenatal diagnosis. Chinese researchers (Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University) conducted a retrospective study of 189,809 NIPT samples collected from 28 provincial-leveled administrative units in China and proved the effectiveness of the method.

Noninvasive prenatal testing (NIPT) can detect aneuploidies and other genetic abnormalities in fetuses are detected through the analysis of cell-free DNA in maternal plasma with highthroughput techniques.

The researchers divided the results for first and second pregnancies. For primiparous and secundiparous women, the mean maternal ages were 28.3 and 34.2 years, respectively

Among the primiparous women, NIPT identified 151 of 152 cases with trisomy 21, with 41 false-positive results; thus the sensitivity was 99.3% and the specificity was 99.9% Among the secundiparous women, NIPT identified 369 of 371 pregnancies with trisomy 21, with 31 false-positive results; thus the sensitivity was 99.5%, and the specificity was 100% .

Among primiparous women, NIPT identified 39 of 41 cases of trisomy 18, with 14 false-positive results, and identified all 10 cases of trisomy 13, with 44 false-positive results. Among secundiparous women, NIPT identified 90 of 91 cases of trisomy 18, with 31 false-positive results, and identified all 16 cases of trisomy 13, with 57 false-positive results. The results indicate that the performance of NIPT for detecting trisomies 18 and 13 in primiparous and secundiparous women is similar.

Besides, the scientists detected significantly higher risk for fetal trisomies 21 and 18 at the maternal age of 39 than at 38.