Epidemiology of low birth weight in Iran: A systematic review and meta-analysis

Introduction: Low birth weight (LBW) is an important general health indicator. The present study was conducted to evaluate the prevalence and risk factors of LBW in Iran. Method: This meta-analysis was reported based on the PRISMA guidelines. All stages were independently performed by two authors. This review is registered with PROSPERO (CRD42020163446). We searched epidemiological studies at international databases of Scopus, Embase, Science Direct, PubMed/Medline, CINAHL, EBSCO, Cochrane Library, Web of Science, and Google Scholar search engine, as well as Iranian databases of SID, IranDoc, Iranian National Library, Barakat Knowledge Network System, RICST and Magiran using MeSH keywords without time limit until 2019. After selecting the studies, applying the inclusion and exclusion criteria, data extraction and qualitative assessment, the data were analyzed based on random effects model using Comprehensive Meta-Analysis Software version 2. P < 0.05 was considered significant. Results: The prevalence of LBW in Iran was 7.95% (95% confidence interval [CI]: 7.36-8.58) in 62 studies with a sample size of 301,839 newborns. The prevalence of LBW in girls and boys was 8.41% (95%CI: 7.47-9.45) and 6.67% (95%CI: 5.86-7.59), respectively. The girls-to-boys odds ratio of LBW was 1.25 (95%CI: 1.13-1.39, P < 0.001) very LBW and extremely LBW prevalence was estimated to be 0.61% (95%CI: 0.40-0.93) and 0.29% (95% CI: 0.18-0.45), respectively. The risk factors for LBW were age of >35 versus [vs.] <= 35 (P = 0.024), age of <18 vs. >= 18 (P < 0.001), education of middle school and lower vs. high school and higher (P < 0.001), weight under 50 kg (P = 0.001), employed vs. housekeeper (P < 0.001), inadequate prenatal care (P = 0.046), interval with previous pregnancy <2 vs. >2 (P < 0.001), prematurity (P < 0.001), history of LBW (P < 0.001), multiple birth (P < 0.001), abortion (P < 0.001), vaginal bleeding (P < 0.001), hypertension (P = 0.001) and preeclampsia (P < 0.001). Conclusion: The results of this meta-analysis showed that LBW is prevalent in Iran. This study can be a national database for LBW that would be of interest to Iranian health policy-makers and planners.