Early pregnancy hyperglycaemia among pregnant women with risk factors for gestational diabetes increases the risk of pregnancy complications.

The current diagnostic criteria for gestational diabetes (GDM) were based on data from women after 24 weeks of gestation, but this may not be equally applicable for earlier gestation. There is insufficient data regarding early pregnancy glycaemia and the associated complications. We retrospectively reviewed 39,483 deliveries and 12,918 with risk factors for GDM underwent oral glucose tolerance test (OGTT) before 24 weeks of gestation. A strong and progressively positive association was observed with any pregnancy complications in both fasting glucose (FG) and 2 h glucose (2hG). The increased risk of developing any pregnancy complications started from FG 4.5-4.7 mmol/L and 2hG of 6.2-6.9mmol/L. Every increase by 1 mmol/L in FG or 2 hG levels increased the risk of developing any complications (aOR 1.614 for FG and 1.131 for 2hG), pre-eclampsia (aOR 1.472 for FG and 1.143 for 2hG), maternal insulin use (aOR 12.821 for FG and 2.366 for 2hG), primary Caesarean section(aOR 1.274 for FG and 1.099 for 2hG), shoulder dystocia (aOR 1.941 for FG and 1.282 for 2hG), macrosomia(aOR 2.203 for FG and 1.072 for 2hG), and large for gestation age(aOR 2.157 for FG and 1.074 for 2hG). Therefore, glycaemic levels in early pregnancy among high-risk women positively associated with pregnancy complications, even at levels below the current recommended diagnostic criteria for GDM.