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CME Credit Offered
CME Credit Offered
Abstract Award
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Poster Session 4

(1055) Frequency and Type of Chromosome Abnormalities in Stillbirths: Insights from More Than 4000 Cases

Friday, January 31, 2025
4:00 PM – 6:00 PM  
Objective: Approximately 1 in 166 pregnancies in the US result in stillbirth (fetal demise >20 weeks’ gestation) and only a minority have a postmortem examination or genetic evaluation. Our objective was to evaluate chromosomal abnormalities detected by single nucleotide polymorphism (SNP)-based chromosomal microarray (CMA) in products of conception (POC) from a large cohort of stillbirths.

Study Design: Retrospective review of 4,990 fresh POC specimens from singleton pregnancies at ≥ 20 weeks’ gestation evaluated 2010-2022. Known pregnancy terminations and livebirths were excluded (278 cases). Illumina CytoSNP-12b SNP-based CMA was used to detect maternal cell contamination (MCC), aneuploidy, triploidy, copy number variants (CNVs), uniparental disomy (UPD), mosaicism, and parental origin of abnormalities.

Results: Of 4,712 samples, 244 (5.2%) had MCC and 37 (0.8%) had an inconclusive result leaving 4,431 samples for analysis. Of these, 517 (11.7%) were abnormal (Table). Median maternal age was 30 and 31 years for normal and abnormal cases, respectively, and median gestational age was 25 and 24 weeks. The percentage of abnormal results increased with maternal age (p < 0.001) but not gestational age (p = 0.34). Triploidy was not observed after 31 weeks’ gestation.  Common autosomal trisomies (T21, T18, T13) were present in 3.9%; monosomy X, 2.6%; CNVs with one or more regions involved, 3.2%; triploidy, 1.0%; and single chromosome UPD, 0.2% (Table).   

Conclusion: Here we report a large dataset of CMA analyses in stillbirth. CMA was successfully performed in approximately 95% of cases (MCC explained most of those without a result). More than 1 in 10 cases had an abnormal finding with a spectrum of abnormalities intermediate between those seen in livebirths and those present in early gestation miscarriages. Many of the findings had implications for future reproductive risk. CMA was useful across all maternal ages and all gestational ages at the time of stillbirth.