Chromosomal abnormalities in primary and secondary recurrent miscarriages: significance for PGT-A

Purpose: To determine the prevalence of embryonic chromosomal abnormalities in patients with recurrent miscarriage (RM) and to assess whether there is a difference between primary and secondary RM. Methods: Retrospective analysis of products of conception (POC) from patients with RM undergoing dilation and curettage. The prevalence of chromosomal aberrations was assessed in 351 POC specimens obtained from 327 patients with a history of three or more pregnancy losses, using quantitative fluorescence polymerase chain reaction (QF-PCR) and chromosomal microarray analysis (CMA). Patients were classified based on their obstetric history: those whose pregnancies all resulted in miscarriage (up to 22 weeks’ gestation) without a prior live birth were categorized as having primary RM, whereas all others were classified as secondary RM. Results: The overall incidence of embryonic chromosomal abnormalities was 47.6%, occurring in 56.7% of primary RM and 44.1% of secondary RM. A significant positive correlation was found between primary RM and embryonic chromosomal abnormalities (p = 0.008), despite the lower mean maternal age. In the secondary RM subgroup, each additional previous pregnancy which developed beyond 22 weeks significantly reduced the likelihood of embryonic chromosomal abnormalities (p < 0.001). Conclusion: Primary RM patients showed a higher prevalence of embryonic chromosomal abnormalities, despite having a lower maternal age. A history of pregnancies progressing beyond 22 weeks was associated with a reduced likelihood of embryonic chromosomal abnormalities.