Maternal third trimester hyperglycaemic excursions predict large-for-gestational-age infants in type 1 diabetic pregnancy

ObjectiveTo determine which maternal glycaemic parameters in type 1 diabetes better predict large-for-gestational-age (LGA) infants.MethodsMaternal glycaemic parameters (mean overall, preprandial, and postprandial glucose; the percentage of glucose readings above and below target and HbA1c levels) of LGA (n = 37) and appropriate-for-gestational-age (n = 36) infants were compared during preconception and each trimester of pregnancy. Logistic regression was used to select predictive variables.ResultsPreconception glycaemic parameters were not different. Mean glucose and the percentage of glucose readings above target were higher in mothers of LGA infants in every trimester of pregnancy. Second and third trimesters mean postprandial glucose, third trimester mean preprandial glucose and third trimester HbA1c were also higher. Only third trimester glycaemic variables were risk indicators of LGA infants: mean glucose (OR: 3.45; 95% CI: 1.52–7.80), mean preprandial glucose (OR: 2.97; 95% CI: 1.34–6.60), mean postprandial glucose (OR: 2.09; 95% CI: 1.19–3.67) and the percentage of glucose readings above target (OR: 1.08; 95% CI: 1.03–1.14). The percentage of glucose readings above target was the best risk indicator.ConclusionsThird trimester glycaemic parameters are more powerful predictors of foetal growth than glycaemic parameters earlier in pregnancy or during preconception. Hyperglycaemic excursions are the strongest predictor of LGA infants.