Association of maternal diabetes mellitus with preterm infant outcomes: a systematic review and meta-analysis

Context The association between maternal diabetes and outcomes of infants who are born preterm is unclear. Objective To perform a systematic review and meta-analysis of clinical studies exploring the association between maternal diabetes and preterm infant outcomes. Methods Medline, PubMed and Cumulative Index of Nursing and Allied Health Literature databases were searched without language restriction from 1 January 2000 until 19 August 2019. Studies examining preterm infants <37 weeks gestational age and reporting prespecified outcomes of this review based on maternal diabetes as primary exposure variable were included. Results Of 7956 records identified through database searches, 9 studies were included in the study. No significant association was found between maternal diabetes and in-hospital mortality (adjusted RR (aRR) 0.90 (95% CI 0.73 to 1.11); 6 studies; participants=1 191 226; I-2=83%). Similarly, no significant association was found between maternal diabetes and bronchopulmonary dysplasia (aRR 1.00 (95% CI 0.92 to 1.07); 4 studies; participants=107 902; I-2=0%), intraventricular haemorrhage or cystic periventricular leukomalacia (aRR 0.91 (95% CI 0.80 to 1.03); 3 studies; participants=115 050; I-2=0%), necrotising enterocolitis (aRR 1.13 (95% CI 0.90 to 1.42); 5 studies; participants=142 579; I-2=56%) and retinopathy of prematurity (ROP) (aRR 1.17 (95% CI 0.85 to 1.61); 5 studies; participants=126 672; I-2=84). A sensitivity analysis where low risk of bias studies were included in the meta-analyses showed similar results; however, the heterogeneity was lower for in-hospital mortality and ROP. Conclusion Maternal diabetes was not associated with in-hospital mortality and severe neonatal morbidities in preterm infants. Future studies should explore the association between the severity of maternal diabetes with preterm infant outcomes.