Value of prenatal chromosomal microarray analysis (CMA) in isolated fetal growth restriction diagnosed before 26 weeks of gestation.

Abstract

Objective: To evaluate the diagnostic yield of amniocentesis with quantitative fluorescent polymerase chain reaction (QF-PCR) and chromosomal microarray analysis (CMA) in pregnancies with truly isolated early-onset fetal growth restriction (FGR) diagnosed before 26 weeks of gestation and to explore associations with perinatal outcomes.

Method: This retrospective cohort study was conducted at a tertiary perinatal centre in Poland. From 1655 amniocenteses performed between 2018 and 2023, we identified 31 singleton pregnancies with isolated FGR (EFW/AC <3th percentile) before 26 weeks, excluding all cases with structural anomalies or major maternal confounders. All cases underwent QF-PCR and CMA. Descriptive statistics and group comparisons were performed.

Results: Abnormal genetic results were found in 9/31 cases (yield 29.0%; 95% CI 14.2–48.0%), including 3 triploidies and 6 pathogenic/likely pathogenic CNVs. CMA provided an incremental yield of 19.4% over QF-PCR alone. One CMA-negative case was diagnosed with hypophosphatasia by postnatal whole-exome sequencing. Mean gestational age at delivery was 32.4 weeks, and adverse perinatal outcomes occurred in 29% of cases.

Conclusion: In isolated early-onset FGR before 26 weeks, QF-PCR combined with CMA achieved a high diagnostic yield of 29%. These findings support routine use of CMA in this high-risk subgroup and highlight the prognostic importance of genetic testing.