Relationship between Maternal Glucose Intolerance and Fasting Plasma Glucose with Macrosomia during Pregnancy

Abstract

Background: In this study, the effects of various degrees of maternal glucose intolerance and Fasting Plasma Glucose (FPG) during pregnancy on the prevalence of macrosomia were addressed.
Methods: In this cohort study, we recruited 1801 pregnant women who referred to perinatal clinic between July 2004 and September 2005. Gestational Diabetes Mellitus (GDM) was diagnosed by oral glucose tolerance test (OGTT) and glucose challenge test (GCT). According to the results of GCT and OGTT, patients were assigned in four groups: 1-normal GCT (<130 mg/dl), 2-GCT ≥ 130 mg/dl but normal OGTT, 3-impaired glucose test (IGT), and 4-GDM. Also, the mean values of infant birth weight (IBW) in each group were recorded. Moreover, by using FPG in the third trimester, patients were classified into four groups: FPGs ≤ 85, 86-90, 91-95, and ≥ 96 mg/dl; and the relationship between the mean FPGs of each group and mean IBW was determined. 
Results: The prevalence of macrosomia in patients with GDM, IGT, only abnormal GCT and normal GCT was 15.8% , 6%, 3.6% and 1.1%, respectively; and the differences between the groups were significant (RR: 2.5; CI95%:1.99-3.12); also, macrosomia positively correlated with obesity before pregnancy (RR: 1.92; CI95%:1.36-2.73). Mean FPG in the third trimester in each group had statistically significant difference regarding to increase prevalence of macrosomia with increase in FPG values.
Conclusion: The lower degrees of glucose intolerance (IGT and Only abnormal GCT) rather than the Carpenter-Coustan criteria could be related with increase in the prevalence of macrosomia, and FPG itself has independent relationship with macrosomia.