Study selection
Inclusion criteria were original studies that reported the
community-based prevalence of infertility. The following exclusion
criteria were applied: (i) irrelevant to prevalence of infertility; (ii)
unable to access full text; (iii) editorials, animal studies, conference
papers, short newsletters, reviews, conference papers, or brief
communications; (iv) conducted in special groups or not population
based; (v) unclear or inconsistently applied definitions of infertility;
(vi) did not distinguishing infertility from childlessness; (vii)
studies that were unclear or no available and numerator denominator. If
several publications used the same dataset, the publication that
provided the most data was selected.
Duplicated studies were removed from the list of literature retrieved in
the first step using Endnote 20.0 software (Clarivate, PA, USA). Second,
two reviewers (Zhou and Li) screened the literature independently in two
stages: title and abstract screening, full-text retrieval followed by
screening according to the inclusion and exclusion criteria.
Disagreements were resolved through discussions between the two
reviewers, or with the help of a third reviewer (Hao).