OR08-01 One-Step Versus Two-Step Approach for Gestational Diabetes Mellitus Screening: Comparison of Maternal and Fetal Outcomes in a Canadian Population
Authors: Goyette Fanny , Wo Bi Lan , Iglesias Marie-Hélène , Rey Evelyne , Godbout Ariane 
Published: May 2020

Screening for gestational diabetes mellitus (GDM) is internationally recommended however there is no universal approach. Impact of the different diagnostic strategies on maternal and neonatal complications’ rates and cost-effectiveness need to be studied.

Objective

To compare maternal and neonatal outcomes between the two supported screening methods for GDM; the International Association of the Diabetes and Pregnancy Study Groups (IADPSG) 75g one-step oral glucose tolerance test (OGTT) versus the 50g two-step OGTT.

Methods

A retrospective cohort study was performed regrouping all deliveries between 2016 and 2018 in two centers, each using one different screening method. GDM was diagnosed in center A when meeting IADPSG odds ratio (OR) 1.75 cut-offs values after a one-step 75g-OGTT. Center B used a two-step strategy and diagnosed GDM with 50g-OGTT 1hr glycemic value ≥11.1 mmol/L or failed 50g followed by 75g-OGTT results over the IADPSG OR 2.0 cut-offs.

Primary outcome was the rate of large for gestational age (LGA) babies. Outcomes were analysed for singleton pregnancies with deliveries &gt;32 weeks.

Subgroup analysis of borderline GDM women (OGTT results in between IADPSG OR 1.75 and 2.0 values) were done. Group A’s borderline patients were treated as per GDM patients. Group B’s borderline patients were not considered diabetic and had normal pregnancy care. Results were adjusted for maternal age, BMI and gestational weight gain.

Results

At interim analysis for the year 2016, a total of 6188 pregnancies, 2664 women in center A (one-step) and 3524 in center B (two-step) were included. The prevalence of GDM was 17.1% in center A (n=456) and 14.8% in center B (n=520). Both populations were comparable in terms of risk factors for LGA except for its ethnic distribution and proportion of obese women (13.1 vs 21.6%). GDM women in center B compared to center A had significant increase in rates of LGA neonates (adjusted OR (ORa) 2.1, p=0.012); neonatal hypoglycemia (ORa 2.1, p=0.0001) and neonatal intensive care unit (NICU) admission (2.1, p=0.048). Gestational hypertension’s rate was more prevalent in center B (ORa 2.1, p=0.020) and there was a non statistical trend towards increased rate of caesareans (1.6, p=0.084).

Regular prenatal care for borderline women in center B (n=94) compared to GDM care in center A (n=150) resulted in increased rate of LGA babies (ORa 3.2, p=0.049). Worse maternal outcomes were identified for gestational hypertension (9.7 vs 1.3%, p=0.035) and preeclampsia (4.3 vs 0%, p=0.021) in group B vs A, respectively.

Conclusions

Choosing the one-step IADPSG criteria’s for GDM screening is associated with lower rates of LGA, neonatal hypoglycemia and NICU admissions, at the expense of increased prevalence in our population. The ongoing study will include a cost-benefit evaluation to assess if improved outcomes overbalance the increased prevalence inherent to lower diagnostic criteria.