Birth Prevalence of Neural Tube Defects in Iran: A Systematic Review

Context: Neural tube defects (NTDs) are one of the most common birth defects with a high rate of mortality. Several studies have shown the reduction of the rate of NTD due to preconceptional usage and flour fortification with folic acid. Objectives: The aim of this systematic literature review was to assess the appropriate information about the prevalence of Neural Tube Defects among the Iranian population, geographic areas of Iran. Data Sources: We searched PubMed, Embase, Scopus, and data banks in Iran, such as the scientific information database (SID), Magiran, and Barekat knowledge network system from January 1969 to February 2017. The following keywords were used to search all fields in the above databases ("Neural Tube Defects" OR "NTD" AND "Iran"). Study Selection: NTDs were classified as given by Moore to include anencephaly, spina bifida, encephalocele, iniencephaly, and craniorachischisis. Primary outcomes of interest for estimating the prevalences were the total number of births (including live and stillbirths if available separately) and the total number of NTD affected births (including live and stillbirths if available separately). Data Extraction: Data extracted from selected studies, included: first author, study design, city, sample size, duration of studies, and the prevalence of NTDs and subtypes of neural tube defects. Results: A total of 429 studies were initially identified in the databases. After excluding duplicate studies, 244 articles were retrieved and reviewed based on their titles and abstracts; 221 articles were excluded. Twenty-three articles were selected for a more detailed review. There were some publications of the same study, data were extracted from the most complete and up-to-date publication. Four articles were added by reference searching and one forthcoming article was added. Finally, 21 articles have been included in the study. Conclusions: The surveillance of NTD in Iran is currently limited due to the fact that provinces have established systems to report national and local NTD prevalence. However, when data are available, reported NTD prevalence, which varies by geographic region from 1.01 to 8.29 per 1000 live births, is in some areas of Iran.