Background and aims: Infertility is one of the most important conditions in reproductive system and there is no reliable estimates for global prevalence of infertility. Therefore, knowing the prevalence of infertility is important and can be effective in decision making. Methods: We systematically reviewed all published papers in Medline database and Scopus (1988–2010). Univariate and multivariate approaches were applied to assess the causes of heterogeneity among the selected studies. Meta-regression was used to examine the relationship between the prevalence of infertility and the year of study. Data manipulation and statistical analyses were performed using Stata 11.1. Results: The study population was not similar in all papers. Studies evaluated the prevalence of infertility in the general population, the total female population, women and couples. Some studies defined infertility as failure to conceive within 12 months of regular sexual life without contraception methods while other studies defined it as failure to conceive within 24 months of regular sexual life without contraception methods. Overall, 52 studies met our inclusion criteria and the pooled worldwide of infertility was obtained about 10. The correlation between prevalence of secondary infertility and year of study was significant (P=0.039). Conclusions: Approximately 10 of the world's population suffers from infertility. Due to the negative impact of infertility on couples in various aspects of life, and the need for treatment and support programs, accurate estimate of infertility is essential worldwide
