Risk of Type 1 Diabetes in the Offspring Born through Elective or Non-elective Caesarean Section in Comparison to Vaginal Delivery: a Meta-Analysis of Observational Studies

Background Caesarean section (CS) has been associated with an increased risk of type 1 diabetes (T1D). The lack of exposure to maternal vaginal and anal microbiome and bypassing the labor process often observed in elective CS may affect neonatal immune system development. This study aims to summarize the effects of elective and non-elective CS on T1D risk in the offspring. Methods A systematic literature search was conducted online for publications providing data on elective and non-elective CS with T1D diagnosis in children and young adults, followed by a meta-analysis from selected studies. Newcastle-Ottawa Scale and GRADEpro tool were applied for quality analysis. Results Nine observational studies comprising over 5 million individuals fulfilled the inclusion criteria. Crude OR estimates showed a 12% increased T1D risk from elective CS compared to vaginal delivery with significant heterogeneity. Adjusted ORs from seven studies did not show T1D risk differences from either CS category, and heterogeneity was detected between studies. Separate analysis of cohort and case-control studies reduced the heterogeneity and revealed a slight increase in T1D risk associated with elective CS in cohort studies (adjusted OR = 1.12 (1.01-1.24)), and a higher increased risk associated with non-elective CS in case-control studies (adjusted OR = 1.19 (1.06-1.34)). Conclusion Summarized crude risk estimates showed a small increased T1D risk in children and young adults born through elective CS compared to vaginal delivery, but with significant heterogeneity. Adjusted risk estimates by study design indicated a slightly increased T1D risks associated with elective or non-elective CS.