Body Fat Index for Obstetric Risk Stratification

Obesity is one of the most common global risk factors for significant health issues, that has become increasingly prevalent among reproductive aged women. In the United States, obesity affects 21% in prepregnant females . Maternal obesity and excessive gestational weight gain have been linked to various adverse obstetric and neonatal outcomes, including spontaneous abortion, gestational diabetes mellitus (GDM), cesarean delivery, preeclampsia, neonatal macrosomia, and complications from surgery and anesthesia . Consequently, contemporary guidelines recommend assessment of body mass index (BMI) at the first prenatal visit to guide diet and exercise directions and stratify obstetric risks . Nevertheless, BMI is associated with limitations to its clinical significance: first, it does not accurately correlate with the body fat distribution and does not differentiate between the increased mass of body muscle, bone, or fat being dependent on the patient's height and weight . Although all pregnant women with obesity is considered at risk of developing an adverse pregnancy outcome , women with BMI \> 30 kg/m2 do not necessarily develop adverse outcomes, while women with BMI \< 30 can still develop significant complications . Therefore, BMI does not present a clinically sensitive tool to screen and predict obesity-relevant adverse outcomes of pregnancy, including GDM, metabolic syndrome, and pre-eclampsia . Anthropometric measurements such as waist circumference, hip circumference, waist/hip ratio, and others have been used to indicate that central fat is associated with the obesity-related adverse outcomes of pregnancy ; however, they are undermined by the subcutaneous fat amount . Computerized tomography (CT) and dual-energy X-ray absorptiometry have been implemented to measure visceral fat in the general population, which is deemed clinically related to health hazards. However, these approaches are associated with radiation exposure, associated with high costs, and are overall not appropriate for screening . Ultrasound is safe during pregnancy and is routinely used as a part of antenatal care. Ultrasound can be used to measure visceral fat with similar sensitivity to CT in measuring fat thickness . Body fat index (BFI) is a novel tool that is calculated using the following formula (BFI = pre-peritoneal fat (mm) x subcutaneous fat (mm) / Height (cm)) . BFI was reported to be a safe, cost-effective, and easy screening method to identify the obesity-related adverse outcomes of pregnancy . Being dependent on pre-peritoneal fat which was reported to correlate with GDM with a predictive advantage over waist circumference and BMI , BFI constitutes a promising screening tool that can assess obesity-related adverse outcomes of pregnancy during first trimester scan without extra-costs and with high patient satisfaction.