Publication:

Correlation of maternal age and combined assessments on risk of chromosomal anomaly during prenatal screening

Background Prenatal detection of genetic abnormalities is one of the biggest challenges of current fetal medicine. Prenatal screening for chromosomal abnormalities can be done using biochemical tests. The screening is a risk estimation test and not a diagnostic test.

Methods Statistical data treatment had been performed on a sample of 362 pregnant women for prenatal screening. This was a retrospective data analysis study undertaken at the National Reference Laboratory, Redcliffe Labs.

Results Nine (2.48%) women out of 362 were screen positive for chromosomopathy. The point biserial correlation between variables (Free β-hCG - Free Beta Human Chorionic Gonadotrophin, PAPP-A- pregnancy associated plasma protein-A and NT-(nuchal translucency) amongst patients with positive and negative screen test was statistically significant. There was a positive correlation between positive screen for chromosomopathy and hCG, MoM, NT MoM whereas a negative correlation between them and PAPP-A. This study indicates that higher values of hCG and lower values of PAPP-A MoM as seen in the positive screen patients is associated with a significant risk of chromosomopathy. A positive correlation between age and screen positive cases was seen. The McNemar’s test indicated a significant reduction in screen positive cases when biomarkers were added to screen for Trisomy 21 in women aged >35 years (n=86). 81 women eventually screened negative.

Conclusions The analyses stresses on the importance of using state-of-the-art, prenatal noninvasive screening software to help provide a predictive outcome, individualized for that pregnant woman.