Factors predictive of macrosomia in pregnancies with a positive oral glucose challenge test: importance of fasting plasma glucose

Abstract

Aim: The study aimed to determine the factors associated with fetal macrosomia following a positive oral glucose challenge test (OGCT).

Methods: In this retrospective single-centre study of 1268 pregnancies with positive 50-g OGCTs (plasma glucose≥130mg/dL, or 7.2mmol/L), gestational diabetes mellitus (GDM) was defined as fasting plasma glucose (FPG)≥95mg/dL (5.3mmol/L) and/or postprandial glucose (PPG)≥120mg/dL (6.7mmol/L).

Results: In GDM pregnancies, the odds ratios adjusted for confounders (age, BMI, ethnicity, parity and weight gain) were 2.02 for macrosomia (Z score≥1.28) and 2.62 for severe macrosomia (Z score≥1.88). For each 10-mg/dL increase in FPG, the mean birth-weight increase was 60g. Macrosomia risk did not differ between GDM patients with normal FPG (<95mg/dL, or 5.3mmol/L) and non-diabetics, but increased significantly in cases of FPG≥95mg/dL and regardless of the level of PPG.

Conclusion: In our study population, birth-weight and macrosomia risk were strongly correlated with FPG, suggesting that it is a simple and efficient marker for the risk of macrosomia.

Keywords: Gestational diabetes mellitus; Macrosomia; Pregnancy; Screening.