Comparison of ultrasound with biomarkers to identify large-for-gestational age in women screened for gestational diabetes mellitus.

Objective: Large-for-gestational-age (LGA) is associated with both fetal and maternal complications. One of the few modifiable risk factors for LGA is Gestational Diabetes Mellitus (GDM); for this reason, fetal growth is usually monitored by ultrasound in the third trimester. This prospective study compared a panel of ten established biomarkers measured at the time of selective screening for GDM at 26-28 weeks gestation with the ultrasound prediction of LGA.
Method: Women were recruited using convenience sampling and consented at the first antenatal visit. Women with maternal risk factors for GDM attended for the one-step 75 g oral glucose tolerance test. An additional blood sample was taken for biomarker measurement. GDM was diagnosed according to the 2013 World Health Organization (WHO) criteria. Fetal biometry, including the abdominal circumference (AC) and the fetal abdominal subcutaneous tissue (FAST) thickness, were measured at 37 weeks gestation.
Results: Of the 195 women included, 105 (53.8%) had GDM. Of the 195 babies, 36 (18.5%) were LGA. Whether the woman had GDM or not, fetal biometry was strongly predictive of LGA but none of the following biomarkers measured at 26-28 weeks gestation alone or in combination were predictive: c-peptide, ghrelin, gastric inhibitory polypeptide, glucagon-like peptide-1 (GLP-1), glucagon, insulin, leptin, plasminogen activator inhibitor-1, resistin and visfatin.
Conclusions: In women diagnosed with GDM, surveillance of fetal growth to identify LGA by ultrasound should continue in the third trimester. None of the ten established maternal biomarkers measured at the time of the OGTT was as strongly predictive of LGA as ultrasound.