Two factors affecting the success rate of the second non-invasive prenatal screening after initial no-call result: experience from a single tertiary center in China

BACKGROUND: One inevitable shortcoming of non-invasive prenatal screening (NIPS)/cell-free DNA (cfDNA) sequencing is the uninterpretable (“no-call”) result, which is mainly caused by an insufficient fetal fraction. This study was performed to investigate the factors associated with a successful second NIPS in these cases and determine the optimal management for women with initial no-call results. METHODS: We retrospectively analyzed the data of women who underwent NIPS with initial no-call results due to an insufficient fetal fraction from 2017 to 2019 in our center. We compared these women's maternal and pregnancy information with the data of women who had attained a successful second NIPS result and women who had received no-call results for a second time. RESULTS: Among the 33,684 women who underwent NIPS, 137 with a no-call result underwent a retest. Comparison between the 87 (63.50%) women with a successful retest and the other 50 (36.50%) women showed a significant difference in both the initial fetal fraction and maternal body mass index (BMI), whereas the other factors showed no significant differences. In addition, with an initial fetal fraction of < 2.00%, the retest success rate was very limited. CONCLUSIONS: We identified two major factors associated with a successful NIPS retest: the initial fetal fraction and the maternal BMI. These findings suggest the need for specialized management for this subset of women and would be instructional for the counseling for these women.