(VP108) THE ASSOCIATION BETWEEN PRE-EXISTING DIABETES AND STILLBIRTH AND PERINATAL MORTALITY: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background: Studies have demonstrated that pregnant individuals with pre-existing diabetes have an increased risk of stillbirth and perinatal death. Despite this well-recognized association, there remain gaps in our knowledge about the magnitude of risk for stillbirth, including its incidence across populations, and factors that may predict its occurrence. The aim of this systematic review was to investigate the relationship between pre-existing diabetes and the risk of stillbirth and perinatal mortality.

METHODS AND RESULTS: Using keywords related to diabetes and pregnancy outcomes, a search strategy was developed in collaboration with a medical librarian. The study protocol was registered in PROSPERO (CRD42022303112). We performed a search of the published literature from inception to April 2022. Study selection and data extraction were performed in duplicate by independent reviewers based on pre-specified inclusion and exclusion criteria. Meta-analyses of summary measures were conducted using random-effect models for included studies.

From 7777 citations, 397 were identified for full text review and 91 met inclusion criteria. Reasons for exclusion at full text review included: gestational diabetes only or gestational diabetes not analyzed separately (n = 92 studies), no control group (n = 76), stillbirth or perinatal mortality not reported (n = 36), zero stillbirths or perinatal mortality (n = 29), wrong study design (n = 29), not French or English (n = 26), and insufficient data for analysis (n = 17). Most included studies were retrospective cohorts (n = 64), followed by prospective cohorts (n = 24), and randomized control trials (n = 3). Meta-analysis of the 37 studies that reported on the association between pre-existing diabetes and stillbirth demonstrated a pooled odds ratio of 3.72 (95% CI 3.09, 4.48; I2 87.6%) [Figure]. Fourteen studies reported on the association of perinatal mortality with pre-existing diabetes, demonstrating a pooled odds ratio of 3.23 (95% CI 2.59, 4.02; I2 79.5%). While most studies demonstrated that pre-existing diabetes increased the odds of stillbirth or perinatal mortality, there was significant heterogeneity in both the stillbirth and perinatal mortality analyses.

Conclusion: Pre-existing diabetes is associated with an over 3-fold increased risk of both stillbirth and perinatal mortality. However, there was significant heterogeneity among the studies. Future analyses will explore possible reasons for this heterogeneity, as well as examine predictors of stillbirth and perinatal mortality, such as type of pre-existing diabetes, treatment modalities, pre-pregnancy care, and smoking.