Impact of maternal body mass index (BMI) and the challenges of fetal echocardiography.

Objectives: Fetal echocardiography is the gold standard modality to detect suspected congenital heart disease (CHD). Accurate diagnosis and subsequent prognosis is even more challenging in the presence of a raised maternal body mass index (BMI). This retrospective study aimed to gain insight into the prevalence of obesity within the cohort of patients referred for fetal echocardiography.

Study Design/methods: Retrospective analysis of all pregnant patients referred to the Scottish National Fetal Cardiology Service between 2015 and 2021 due to a suspected fetal cardiac abnormality and examining the associated trends in maternal BMI and the Scottish Index of Multiple Deprivation (SIMD).

Results: BMI data were available for 962 (96.3%) of the 998 patients referred during the study period. Median BMI during the study period was 31. BMI range in the seven-year period was 16-63. There was no association between BMI group and year (P = 0.889). A median of 58% of patients referred were classified as overweight (BMI > 25 kg/m), and only 37% were reported to have a BMI within normal limits. Referral BMI was relatively consistent in the seven years with no dramatic increase in the obese categories. Mean BMI in SIMD 5 (lowest level of deprivation), was significantly lower (P = 0.001), than in SIMD 1 (highest deprivation).

Conclusions: People of child bearing age should be aware the potential limitations that a raised BMI may have upon diagnostic/screening accuracy impacting subsequent ability to provide accurate fetal cardiac diagnoses and prognostic fetal cardiac imaging.