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Sara Masihi , Parisa Gorjinezhad^* , Mojgan Barati , Mahin Najafian , Elham Farhadi

Abstract

Cell-free DNA(CFDNA)  is one of the diagnostic methods used in the trimesters of pregnancy to screen for chromosomal abnormalities. This study investigates and compares CFDNA and amniocentesis results and several factors affecting CFDNA results in a specified period.The present study was conducted on all pregnant mothers who underwent CFDNA tests due to high-risk screenings in the first or second stage of pregnancy or for any other reason. Based on this, about 2300 pregnant mothers with CFDNA tests were selected and included in the study by census, and the abnormal answers obtained after performing the diagnostic test were analyzed, which included false negative, false positive, and abnormal results. The cases that were not reported, especially the cases where the diagnostic test is performed due to the low fetal fraction, were investigated. 90 high-risk cases were investigated.The results revealed a statistically significant relationship between patients' weight and CFDNA results (p<0.05). The results also revealed that the highest sensitivity and specificity were related to trisomy 21 (Down syndrome). Also, a significant relationship was found between the numerical decrease in fetal fraction (less than 5) and the CFDNA result. However, no correlation was found between the number of pregnancies and the mother's gravidity and the CFDNA response.Thus, it seems to be the best screening method in suspected cases of Down syndrome. However, unlike other studies, no significant relationship was observed between BMI and CFDNA results in our study‎.