Impact of maternal obesity and maternal overweight on the detection rate of fetal heart defects and the image quality of prenatal echocardiography.

Purpose: The purpose of this study was to compare the prenatal detection of four congenital heart defects (CHDs) and the image quality of five corresponding ultrasound planes among obese, overweight and normal-weight women.

Materials And Methods: This was a retrospective cohort study of 54,846 pregnancies undergoing fetal echocardiography between 18 and 37 weeks of gestation in the years from 2000 to 2007. The women were categorized according to pre-pregnancy body mass index (BMI) as normal-weight (BMI < 25), overweight (BMI 25 - 29.9) and obese (BMI ≥ 30). Image quality and prenatal detection of atrioventricular septal defect (AVSD), double outlet right ventricle (DORV), tetralogy of fallot (TOF) and dextro transposition of the great arteries (D-TGA) were evaluated in the BMI strata.

Results: 108 cases with one of the considered CHDs were identified. The prevalence was significantly higher (relative risk = 2.04) in overweight or obese women (57/19,404 vs. 51/35,442, p < 0.0002) than in normal-weight women. In total 86.1% of CHDs were correctly identified prenatally (93/108, CI: 79.6%-92.6%), 84.3% (43/51) in the normal weight group, 88.6% (39/44) in the overweight group and 84.6% (11/13) in the obese group. The rate of insufficient ultrasound images increased from 6.4% in normal-weight patients to 17.4% in obese women within the 108 CHD cases.

Conclusion: The prenatal detection of fetal AVSD, DORV, TOF and D-TGA was also satisfactory in overweight and obese patients, but image quality substantially decreases with an increasing maternal BMI. If there is a BMI-associated difference in the detection rate, it probably will not exceed 20%.