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Prenat Diagn. 2010 Jan;30(1):14-22. doi: 10.1002/pd.2399.

Influence of maternal BMI on genetic sonography in the FaSTER trial.

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University of Utah, Salt Lake City, UT, USA.



We sought to evaluate the influence of maternal body mass index (BMI) on sonographic detection employing data from the FaSTER trial.


Unselected singleton pregnancies underwent detailed genetic sonogram to evaluate for structural fetal anomalies and soft markers for aneuploidy. BMI (kg/m(2)) were calculated from reported initial visit values. Sensitivity, specificity, false positive and false negative rates (FPR and FNR), likelihood ratio, detection rates, and a missed diagnosis rate (MDR: FNR + marker recorded as 'missing'/N) were calculated.


Eight thousand five hundred and fifty-five patients with complete BMI information had detailed genetic sonography. A lower sensitivity with an elevated FNR and MDR was observed in obese women for multiple aneuploid markers (e.g. > or =2 markers 32% sensitivity with 68% FNR among BMI <25 vs 22% and 78% among BMI >30). Similarly, the detection rate for cardiac anomalies among women at BMI <25 was higher (21.6%) at a significantly lower FPR (78.4%; 95% CI 77.3-79.5%) in comparison to obese women (8.3% with FPR 91.7%; 95% CI 90.1-93.2%). In a logistic regression model, maternal obesity significantly decreased the likelihood of sonographic detection of common anomalies (adjusted OR 0.7; 95% CI 0.6-0.9; p = 0.001).


The performance of second trimester genetic sonography is influenced by obesity, with a significantly higher MDR for multiple minor markers and lower likelihood for detecting common anomalies.

[Indexed for MEDLINE]

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