The risk factors of meconium aspiration syndrome in newborns: a meta-analysis and systematic review

Abstract

Background: Risk factors related to meconium aspiration syndrome (MAS), that were understated or unanalyzed by previous comprehensive studies, have emerged. The aim of the study is to determine the maternal, peripartum and fetal-neonatal risk factors with a meta-analysis method, to provide a more extended vision on high-risk scenarios related to MAS development and an insight for further research. Methods: Articles were obtained by searching the PubMed, Ovid MEDLINE, Embase.com, Scopus, Web of science, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials databases, yielding 2,090 records from 1978 to 2022. Inclusion criteria of eligible studies were reported on the risk factors for the outcome of MAS within any population; using non-MAS group as control; and providing the sample size and raw data. Risk of bias of the included studies were assessed by Newcastle-Ottawa quality assessment scale. Meta-analysis on pooled odds ratios (ORs) on the extracted risk factors from the literature were calculated by Mantel-Haenszel or Inverse Variance method. Results: A total of 55 references, including case-control studies (n=17) and observational cohort studies (n=38), were included. The majority of cohort studies, but not case-control studies, were at low risk of bias. Fifteen risk factors were included, of which 6 were related to maternal status, 3 to peripartum status and 5 to fetal-neonatal status. All factors but gender of infant were significant impactor. The factor with the largest valid effect size was Apgar <7 at 5 min [8 studies, OR 14.89, 95% confidence interval (CI): 9.52–23.28, P<0.001]. Induction of labor was a protective factor (6 studies, OR 0.56, 95% CI: 0.47–0.68, P<0.001). Maternal body mass index (BMI) ≥30 kg/m2 (5 studies, OR 2.27, 95% CI: 1.53–3.35, P<0.001) was a risk factor. Smoking was an unneglectable risk factor that was understated with only one adjusted OR available (1 study, OR 1.47, 95% CI: 1.32–1.64). Conclusions: The reported factors can be considered as impactors for MAS development by clinicians. Maternal smoking and obesity were understated and should be emphasized and controlled in further clinical practice. The limited quality of relevant case-control studies necessitates further high-quality researches (CRD 42022338176).