Association of a failed noninvasive prenatal screening with the risk of cytogenetic abnormalities in a general‐risk population: A retrospective cohort study

OBJECTIVE: To investigate whether noninvasive prenatal screening (NIPS) failure in a general-risk population is associated with an increased likelihood of cytogenetic abnormalities. METHODS: This was a retrospective observational cohort study at a tertiary center, based on a general-risk population. Singleton pregnancies that underwent NIPS between May 12, 2017, and July 30, 2021, at the Obstetrics and Gynecology Hospital of Fudan University, Shanghai, China, were included. The outcomes were the incidence of common autosomal aneuploidies (trisomy 21, 18, or 13), sex chromosome aneuploidies (SCAs), and copy number variations (CNVs) on the first attempt. From the reports of NIPS, the pregnancies with a failure were compared with those with a success. Propensity score overlap weighting was applied to adjust for maternal age, paternal age, parity, body mass index, method of conception and gestational age at the first blood collection. RESULTS: Of the 42 121 pregnancies included, 41 776 (99.18%) received reports and 345 (0.82%) did not on the first attempt at NIPS. Pregnancies with NIPS failure showed no significantly statistical difference in the risk for trisomy 21, 18, or 13 (0.29% vs. 0.23%; overlap weighting risk ratio [OW RR] 1.17; 95% CI 0.16-8.46), SCAs (4.08% vs. 7.89%; OW RR 0.53; 95% CI, 0.13-2.26) and CNVs (6.12% vs. 8.13%; OW RR 0.76; 95% CI, 0.23-2.53), compared with those with successful NIPS. These findings remained consistent in the sensitivity analyses. CONCLUSIONS: The evidence was insufficient that NIPS failure after first-trimester ultrasound screening could be associated with an increased risk of common autosomal aneuploidies, SCAs, and CNVs. Our findings suggest that in a general-risk population those who experience NIPS failure need to be managed on the basis of their basic risk.