Pregnancy Outcomes in Type 2 Diabetes: a systematic review and meta-analysis

Type 2 diabetes (T2D) now accounts for the majority of pre-existing diabetes affecting pregnancy in the UK. Our aim was to determine its impact on pregnancy outcomes compared to type 1 diabetes (T1D), gestational diabetes (GDM) and non-diabetes pregnancies. PubMed was searched 1 January 2009-2024. Cohort observational studies reporting original data on at least one of the primary outcomes in ten or more T2D pregnancies were eligible for inclusion. Comparative diabetes and non-diabetes pregnancies were also collected. Primary outcomes included congenital anomalies, stillbirths, neonatal and perinatal mortality, birthweight, rates of large for gestational age (LGA), small for gestational age (SGA) and macrosomia. PROSPERO ID CRD42023411057. 47 studies were analysed. The number of pregnancies in each analysis varied depending on the available data from the outcome being analysed but ranged from 723 to 4,469,053 pregnancies. When compared with T1D pregnancies, T2D were more likely to have SGA babies as well as greater neonatal and perinatal mortality (OR 2.29, 95% CI 1.12 – 4.67; OR 1.53 95% CI 1.20 to 1.94 and OR 1.31 95% CI 1.07 to 1.61 respectively). When compared with GDM, T2D were more likely to have babies with congenital anomalies (OR 1.91, 95% CI 1.04 – 3.50), LGA (OR 3.49, 95% CI 2.49 to 4.89), neonatal mortality (OR 3.96, 95% CI 3.38 to 4.64) and stillbirth (OR 16.55, 95% CI 5.69 to 48.11). In comparison to non-diabetic pregnancy, T2D were more likely to have babies with congenital anomalies (OR 1.76, 95% CI 1.11 – 2.79), LGA (OR 2.79, 95% CI 1.93 to 4.04), perinatal mortality (OR 4.18, 95% CI 2.91 to 6.01) and stillbirth (OR 7.27, 95% CI 3.01 to 17.53). T2D pregnancies are associated with a greater perinatal mortality than other forms of diabetes in pregnancy. Given its increasing prevenance, greater awareness of the adverse pregnancy outcomes associated with T2D is needed, by both healthcare providers and policy makers, to improve care.