Pre-pregnancy body mass index in mothers, birth weight and the risk of type I diabetes in their offspring: A dose-response meta-analysis of cohort studies

Background: The incidence of type I diabetes among children has increased significantly and the relationship between maternal pre-pregnancy Body Mass Index (BMI), Birth weight and risk of Type 1 diabetes in children (T1DMC) is controversial. Objective: This dose-response meta-analysis was performed to investigate the association between maternal Pre-Pregnancy Body-Mass Index, Birth Weight and the Risk of Childhood Type I Diabetes. Search strategy: A comprehensive systematic search was conducted in MEDLINE/PubMed, SCOPUS, Cochrane, and Web of Science databases from inception to April 2019. Key search terms included body mass index OR Birth weight AND Type 1 diabetes. Selection criteria: Peer-reviewed studies that reporting association between BMI or birth weight and type I diabetes in a retrospective or prospective study by appropriate estimates such as the hazard ratio (HR), risk ratio (RR), or odds ratio (OR) and the corresponding 95 % confidence intervals (CI). Data collection and analysis: MOOSE guidelines were followed. Data were extracted by 2 researchers, independently. Combined hazard ratios (HRs) was evaluated by DerSimonian and Laird Random-effects model. Results: Two studies continuing four arms with 1,209,122 participants were eligible for pre-pregnancy BMI section meta-analysis and six studies were eligible for inclusion, providing 10,340,036 participants for birth weight section meta-analysis. Pooled results demonstrated a significant association between obesity and risk of T1DMC (HR: 1.30, 95 % CI: 1.16-1.46, I2 = 7%). The combined HR (95 % CI) showed lower risk of T1DMC in low birth weight infants (HR: 0.78, 95 % CI: 0.69-0.88, I2 = 0%) and higher risk of T1DMC in the high birth weight infants versus the normal category of birth weight (HR: 1.08, 95 % CI: 1.00-1.17, I2 = 31 %). There was a significant non-linear association between birth weight and risk of T1DMC in children (Coef=-0.00032, p = 0.001). Conclusions and relevance: This systematic review and meta-analysis identified high maternal BMI and High birth weight (HBW) increase risk of childhood T1DMC. (C) 2020 Elsevier Masson SAS. All rights reserved.

Automated summary

This study found that high maternal BMI and high birth weight increase the risk of childhood Type 1 diabetes. Additionally, infants with lower birth weight have a lower risk, while infants with higher birth weight have a higher risk.