Impact of maternal obesity on the risk of preterm delivery : insights into pathogenic mechanisms

Purpose: Preterm delivery (PTD) represents the leading cause of neonatal death and disability. Among risk factors for PTD, maternal obesity (MO) is becoming an ever more relevant condition in developed countries, although the mechanisms relating this condition to higher risk of PTD is not clear. Aim of this narrative review is to summarize evidences from clinical and translational research showing how MO might negatively impact on pregnancy and neonatal outcomes, particularly, by increasing the risk of PTD. Methods: We performed comprehensive review of the literature in PubMed and Google Scholar databases for studies from 1998 to 2018 linking MO to PTD and inflammation. Results: Chronic inflammatory status associated to increased synthesis of adipokines and cytokines from fat tissue has been shown in obesity. Obese women have a higher risk of both spontaneous and medically induced PTD. In about 50% of cases of spontaneous PTD, an infection-induced chorion amnionitis can be detected while in the remaining 50% a sterile inflammatory response has been described. Activation of uterine innate immunity system in intra-amniotic cavity and in chorioamniotic membranes might represent the missing link between MO and the pathogenesis of PTD. Conclusion: Tissue inflammation might represent the pathogenic link between MO and increased occurrence of PTD. The achievement of pre-pregnancy normal maternal weight and body mass index is a fundamental aim of public health to reduce the incidence of PTD and get optimal reproductive outcomes.