Outcomes of pregnancies in women with pre‐gestational diabetes mellitus and gestational diabetes mellitus; a population‐based study in New South Wales, Australia, 1998–2002

AIM: To determine population-based rates and outcomes of pre-gestational diabetes mellitus (pre-GDM) and gestational diabetes mellitus (GDM) in pregnancy. METHODS: This was a cross-sectional study, using linked population databases, of all women, and their infants, discharged from hospital following birth in New South Wales (NSW) between 1 July 1998 and 31 December 2002. Women with, and infants exposed to pre-GDM or GDM were compared with those without diabetes mellitus for pregnancy characteristics and outcomes. RESULTS: Women with a singleton pregnancy (n = 370,703) and their infants were included: 1248 women (0.3%) had pre-GDM and 17,128 (4.5%) had GDM. Of those women with pre-GDM, 57% had Type 1 diabetes, 20% had Type 2 diabetes and for 23% the type of diabetes was unknown. Major maternal morbidity or mortality was more common in women with pre-GDM (7.9%) [odds ratio (OR) 3.2, 95% confidence interval (CI) 2.6, 3.9] and in women with GDM (3.1%) (OR 1.2, 95% CI 1.1, 1.4) when compared with women without diabetes (2.6%). Major infant morbidity or mortality occurred more frequently in infants exposed to pre-GDM compared with no diabetes (13.6% vs. 3.1%) (OR 5.0, 95% CI 4.2, 5.8) and in infants exposed to GDM compared with no diabetes (3.2% vs. 2.3%) (OR 1.4, 95% CI 1.3, 1.5). CONCLUSIONS: Pre-GDM and GDM continue to be associated with an increased risk of adverse maternal and neonatal outcomes; however, women with GDM have adverse outcomes less frequently. Rates of GDM and pre-GDM appear to be increasing over time. Clinicians should consider the potential for adverse outcomes, and arrange referral to appropriate services.