Prenatal karyotype analysis of 8245 amniotic fluid samples of Iranian women and report of their chromosomal abnormalities: A 15-year single-center study

Aims: The aim of this study was to assess the prevalence of different chromosomal abnormalities in amniotic fluid samples of Iranian women referred to Sarem Women's hospital.Besides, to identify different indications of referral and the prevalence of abnormalities in each category, and assigning the abnormality rate to mothers' age, of 35 years and above and less than 35.Material and Methods: 8245 amniotic fluid samples of women were referred to Sarem women's hospital from March 2006 to March 2022.After receiving genetic counseling, theywere referred for cytogenetics investigation.Findings: 4.8% of samples had chromosomal abnormalities of which 70.45% were numerical and 29.55% were structural.The most common numerical abnormality was trisomy 21 accounting for 36.11% of all abnormal cases and 51.25% of numerically abnormal cases.Abnormal Maternal Serum Screening Test (AMSST) was found to be the major indication of referral with 76.5% of all referrals.46.71 % and 53.29% belonged to the <35 and ≥35 age groups, respectively with trisomy 21 responsible for 45.02% of abnormalities in women of ≥35 age and structural abnormalities of 29.18 % of women <35.Conclusion: This study emphasizes prenatal screening and cytogenetic testing for chromosomal abnormalities.Furthermore, the high level of both numerical and structural chromosomal abnormalities in women of both age groups highlights the significance of cytogenetic testing for all pregnant women regardless of their age.