Long-term Risk for Type 1 Diabetes and Obesity in Early Term Born Offspring: A Systematic Review and Meta-Analysis

Context: Prematurity increases the long-term risks for endocrine and metabolic morbidity of offspring, but there is uncertainty regarding the risks for early-term deliveries (370/7-386/7 weeks of gestation). Objective: We aim to evaluate whether early-term deliveries increase the long-term risk for type 1 diabetes and obesity of offspring up to the age of 18 years compared with full-term children. PubMed, Medline, and EMBASE were searched. Observational cohort studies addressing the association between early-term delivery and long-term risk for type 1 diabetes and obesity, were included. Two independent reviewers extracted data and assessed risk of bias. Pooled relative risks (RRs) and heterogeneity were determined. Publication bias was assessed by funnel plots with Egger's regression line and contours, and sensitivity analyses were performed. Results: Eleven studies were included following a screen of 7500 abstracts. All studies were scored as high quality according to the Newcastle-Ottawa Quality Assessment Scale. Early-term delivery was significantly associated with an increased risk for type 1 diabetes (RR 1.19, 1.13-1.25), while the association was weaker for overweight and obesity (RR 1.05, 0.97-1.12). It is challenging to determine whether the association between early-term births and long-term morbidity represents a cause and effect relationship or is attributable to confounders. Most of the included studies adjusted for at least some possible confounders. Conclusion: Compared with full-term offspring, early-term delivery poses a modest risk for long-term pediatric type 1 diabetes. Our analysis supports that, whenever medically possible, elective delivery should be avoided before 39 completed weeks of gestation.