INTRODUCTION
Gestational diabetes (GDM) is defined as glucose intolerance first diagnosed in pregnancy(1). Risk factors include maternal age, ethnicity, family history of diabetes and obesity. Notably, a history of prior GDM confers an estimated 30-60% risk of recurrent GDM(2) (3-5)(6, 7).
GDM is associated with adverse effects for both mother and fetus, including pre-eclampsia, polyhydramnios, shoulder dystocia, preterm birth, increased rate of neonatal intensive care admission, neonatal hypoglycemia, jaundice and respiratory distress, small for gestational age (SGA) and large for gestational age (LGA) babies(8, 9). The risk of these complications in a second GDM pregnancy has not been defined. Only three studies have examined the risk of maternal or fetal complications in recurrent GDM(10-12).
One retrospective study of 389 women observed higher fasting glucose levels and pre-pregnancy BMI in the second GDM pregnancy compared to the first, a non-significant increase in LGA and no increase in adverse neonatal outcomes(10). In another retrospective study, LGA rates were similar in pregnancies with first-time and recurrent GDM(12). Both studies did not examine individual level data to determine if women having adverse outcomes in the first pregnancy had a higher risk of the same outcomes in their second pregnancy- information which is pertinent to the practical management of women with recurrent GDM. In contrast, a third study of GDM pregnancy pairs found a higher rate of LGA in the subsequent pregnancy compared to the index (22.4% vs 13.8%) (11). 41.5% of women with LGA in the index pregnancy went on to have another LGA baby.
The aims of this study were to quantitate the risk of adverse delivery outcome (ADO) and adverse neonatal outcome (ANO) in consecutive GDM pregnancies. More specifically, we assessed the predictive value of adverse outcome in the index GDM pregnancy on the next GDM pregnancy, and the relationship with other risk factors such as maternal BMI, interpregnancy weight gain and interpregnancy interval. This is important as discerning risk factors conferring a worse outcome in women with a second GDM pregnancy will identify subgroups of women who might benefit from earlier GDM screening or more directed therapy in their next pregnancy.