Relationship between 50-g glucose challenge test and large for gestational age infants among pregnant women without gestational diabetes.

The study aimed to compare the incidence of large for gestational age (LGA) infants between women with a false positive and normal glucose challenge test (GCT), and to evaluate the factors associated with LGA. A total of 480 pregnant women at risk for gestational diabetes mellitus (GDM); 160 with a false positive GCT and 320 with normal GCT results were included. The incidence of LGA and other pregnancy outcomes were compared between the two groups. Possible associated factors for LGA were also evaluated. Women with a false positive GCT were significantly older and more likely to be multiparous. The incidence of LGA was comparable between the false positive and normal GCT groups (15.6% vs. 13.1%, p = .456). Other pregnancy outcomes were also comparable. Logistic regression analysis showed that pre-pregnancy underweight significantly reduced the risk of LGA (adjusted OR 0.25, 95% CI 0.07-0.87, p = .029) while a second trimester weight gain >7 kg significantly increased the risk of LGA (adjusted OR 3.13, 95% CI 1.67-5.89, p < .001). Impact Statement What is already known on this subject? Women with a false-positive GCT (abnormal GCT but normal OGTT) can be considered as having an early form of glucose intolerance which similar adverse outcomes to GDM could develop. Previous studies have reported that a mild maternal hyperglycaemia in the absence of GDM is associated with LGA, macrosomia, shoulder dystocia and a caesarean delivery. There is no current recommendation for any intervention or treatment among women with a false positive GCT. What the results of this study add? The results of this study showed that an incidence of LGA was not significantly increased in the false positive GCT groups and that other pregnancy outcomes were comparable. A pre-pregnancy underweight significantly reduced the risk of LGA while a second trimester weight gain >7 kg significantly increased the risk of LGA. What the implications are of these findings for clinical practice and/or further research? As a gestational weight gain is modifiable, behavioural and a dietary intervention as well as a close monitoring of the weight gain could help in lowering the risk of LGA, even in the absence of GDM. Further studies which are more widely generalisable are needed to elucidate the relationship between 50 g GCT and the adverse outcomes and to investigate the benefits of a specific intervention among this specific group of women.