Maternal Blood Adipokines and Their Association with Fetal Growth: A Meta-Analysis of the Current Literature

Background: Assessing fetal growth constitutes a fundamental aim within the realm of prenatal care. Impaired prenatal growth increases the risk of perinatal mortality, morbidity, and poor newborn outcomes. Growth restriction increases the risk of premature birth problems, as well as the risk of poor neurodevelopmental outcomes and future non-communicable disorders such as hypertension and metabolic syndrome as adults. The objective of this systematic review is to accumulate current literature evidence to assess the patterns of serum adipokine levels among women with growth-restricted fetuses and assess their potential alterations in those high-risk pregnancies. Methods: Medline, Scopus, CENTRAL, Clinicaltrials.gov, and Google Scholar databases were systematically searched from inception until 31 March 2023. All observational studies reporting serum adipokine values among women with appropriately grown and growth-restricted fetuses were held eligible. Results: The current systematic review encompassed a total of 20 studies, incorporating a patient population of 1850 individuals. Maternal blood leptin emerged as the adipokine most investigated, as evidenced by 13 studies encompassing a collective sample size of 1081 patients, all of which explored its potential correlation with intrauterine growth restriction. Elevated levels of leptin were detected in fetuses with intrauterine growth restriction, although the observed difference did not reach statistical significance. Furthermore, regarding adiponectin, the meta-analysis conducted indicated that there were not any statistically significant differences observed in the mean values of adiponectin. The available data on the remaining three adipokines were extremely limited, making it difficult for any solid conclusions to be extracted. Conclusions: Though limited and inconsistent, the existing data suggest that fetal growth restriction is not linked to leptin, adiponectin, visfatin, resistin, or RBP4. More substantial prospective studies are needed to comprehend the importance of established and novel adipokines.