New guidelines for screening, diagnosing, and treating gestational diabetes - evaluation of maternal and neonatal outcomes in Finland from 2006 to 2012

Introduction: In this study, we have assessed the changes in pregnancy outcomes following the implementation of national guidelines for gestational diabetes mellitus (GDM). These national guidelines changed the screening policy from risk-based to comprehensive screening.

Material and methods: We designed a retrospective register-based cohort study based on the data from the Finnish Medical Birth Register and Hospital Discharge Register including 34 794 singleton births in 2006-2008 and 36 488 in 2010-2012. Maternal characteristics and pregnancy outcomes were analyzed.

Results: Overall, 29.6% of mothers underwent an oral glucose tolerance test in 2006-2008 compared with 59.7% in 2010-2012. The prevalence of GDM increased from 7.2 to 11.3% and was highest among obese women (body mass index ≥30 kg/m² ) (from 30.0 to 34.7%; p < 0.001). The proportion of insulin-treated women remained unchanged (12.5/12.3%; p = 0.70). The main pregnancy outcomes for the women with GDM were the increased usage of oxytocin (19.5/40.0%, p < 0.001), increased number of inductions (27.2/33.0%; p < 0.001) and reduced birthweight (mean ± SD: 3647 ± 575 g/3567 ± 575 g). Healthy and unscreened women displayed similar results. Children of both women with GDM and healthy screened women had fewer admissions to the neonatal intensive care unit (16.3%/12.1%; p < 0.001) and less asphyxia (11.3%/6.3%; p < 0.001). However, the rates of cesarean delivery (26.5%/25.4%, p = 0.31), resuscitation (2.6%/2.0%; p = 0.12), and perinatal mortality (1.2‰/3.1‰, p = 0.11) among women with GDM did not change, whereas the number of hypoglycemia cases increased (2.3%/5.2%; p < 0.001).

Conclusions: In conclusion, glucose tolerance tests were performed twice as often as a result of the implementation of the national GDM guidelines, but this comprehensive screening practice did not improve pregnancy and neonatal outcomes.