Impact of the maternal age on first trimester screening for chromosomal aberrations of the fetus – Analysis of 15,228 datasets

Introduction: First trimester screening (FTS) became standard in noninvasive

testing for chromosomal abnormalities in early pregnancy.^{1 2} The

individual risk is calculated on the basis of a general background risk, which

refers to the maternal age.³ A new method, Advanced Firsttrimester Screening

(AFS) excludes the background risk in its algorithm.^{4 5 6} This study had the aim

to analyze how the detection of aneuploidies is influenced by the in- or

exclusion of the maternal age in the risk calculation.

Material and Methods: The data of 15,228 first trimester screenings were

recalculated with FTS and AFS. The study cohort was divided by age into

nine groups and the numbers of detected cases were recorded according to

the groups of age.

Results: 90% of 129 detected aneuploidies reached identical test results, independent from in- or exclusion of maternal age in risk calculation. FTS detected five aneuploidies at age 35 or older that were not detected

by AFS. AFS detected six aneuploidies that were not detected by FTS. Out of

these, the oldest mother was 32 years old.

Discussion: With the exclusion of maternal age from risk calculation, the

detection of aneuploidies showed a shift from older to younger women.

Overall, the detection rate did not change significantly. However, the false

positive rate was 25% lower with the exclusion of maternal age.

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