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.