Comparative Cytogenetic Analysis of Spontaneous Abortions in Recurrent and Sporadic Pregnancy Losses

BACKGROUND: The majority of miscarriages are sporadic; however, 1–5% of couples experience recurrent pregnancy loss (RPL). Approximately 50–60% of miscarriages result from chromosomal abnormalities. Currently, there are conflicting reports regarding the rates of chromosomal abnormalities between recurrent and sporadic pregnancy losses. METHODS: A retrospective comparative cytogenetic analysis of 442 RPL and 466 sporadic abortions (SA) was performed. Maternal age and medical background were evaluated, and chromosomal abnormality rates were compared between groups. RESULTS: The frequency of embryos with abnormal karyotypes was significantly higher in SA compared to RPL (56.7 and 46.6%, respectively), and abortions from women under 30 years of age were the main contributor to this difference. An age-dependent increase in the abnormal karyotype rate was observed in two groups of women - those with SA [53.0 and 70.1% for younger and older (≥35-year-old) mothers, respectively] and those with idiopathic RPL without any concomitant reproductive pathology (46.5 and 78.4% for younger and older mothers) - but not in the group of women with RPL associated with concomitant reproductive pathology. The incidence of recurrent abnormal karyotypes in subsequent miscarriages was significantly higher than random probability (odds ratio = 22.75). CONCLUSION: Our findings highlight the variability in the risk of aneuploidy in recurrent abortion.