The Relationship between Screening Markers in the First Trimester of Pregnancy and Chromosome Aberrations

This study was designed and performed to investigate the relationship between fetal chromosome aberrations and screening markers in the first trimester of pregnancy in order to prevent the birth of infants with chromosome aberrations with early prenatal diagnosis.

We conducted an analytic cross-sectional study on result of chromosomal culture of 762 pregnant women with high-risk combined screening test from December 2018 to June 2020 and analyzed by SPSS program.

There was a significant relationship between chromosome structural abnormalities with free beta-human chorionic gonadotropin (free β-hCG) values equal to and higher than 1.5 multiples of the median (MoM) (P: 0.05). The highest incidence of disorder in number of chromosomes with abnormal nuchal translucency (NT) percentiles (≥99%) was seen (P < 0.001). It also shows that the cumulative number of chromosome aberrations of 25 (78.12%) occurred in individuals with a NT less than 99^th percentile and at the same time a risk of 1/50≤ risk <1/10.

According to the results, Comparative Genomic Hybridization (CGH) array method is recommended to detect structural abnormalities in chromosomes in samples with NT ≥3.5. In addition, it is noteworthy that chromosomal structural abnormalities occur in free β-hCG ≥1.5 MoM.

Due to the frequency of chromosomal structural disorders and its effect on the incidence of fetal abnormalities, the study of chromosomal structural disorders is recommended.