Pregnancy outcomes and maternal characteristics in women with pregestational and gestational diabetes: a retrospective study on 206,917 singleton live births.

AIMS: To examine risk of adverse pregnancy outcomes, mothers' characteristics and incidence rate over time of pregestational type 1 (T1D), type 2 (T2D) or gestational diabetes (GDM).

METHODS: The study included all singleton live births born from women aged 15-45 year, in Tuscany, Italy from 2010 to 2018. Pregnancy outcomes were retrieved by certificates of care at delivery compiled by midwives. Pregestational diabetes and GDM were identified by regional administrative databases. Time course of pregestational diabetes and GDM across last decade was assessed by Poisson analysis. Logistic regression analysis was used to calculate adjusted odds ratios (OR; 95% CI) for maternal characteristics or neonatal outcomes.

RESULTS: Among 206,917 singleton live births, GDM was diagnosed in 21,613 pregnancies (10.46%) and pregestational diabetes in 979, being T2D more prevalent than T1D (606; 0.29% vs. 373; 0.18%). Pregestational T2D incidence progressively decreased over last decade, T1D remained stable while GDM progressively rose. Pre-pregnancy obesity, preterm deliveries or cesarean sections were common characteristics of pregestational diabetes and GDM. Risk of neonatal distress and neonatal malformations was higher in pregestational T1D. Risk of prior spontaneous abortions was higher in GDM and in pregestational T2D (OR: 4.19; 3.30-5.33), mostly treated with metformin. Risk of neonatal macrosomia was increased only in pregestational diabetes.

CONCLUSIONS: In our population, pregestational T2D was more prevalent than T1D. Neonatal complications were mostly associated with pregestational T1D. Increased risk of previous spontaneous abortions was the hallmark of pregestational T2D. GDM, even if sharing adverse outcomes with pregestational T2D, was unrelated to rise in risk of neonatal macrosomia.