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.