title: [A prevalence survey of infertility in Beijing, China].
abstract: OBJECTIVE
  To investigate the prevalence of infertility and its risk factors in the fertile-age couples of Beijing, China.
  
  
  METHODS
  A cross-sectional survey on the prevalence and risk factors was conducted from July 2007 to May 2008 in 7 Beijing districts. The districts were subdivided into the administrative units of "communities". A total of 33 communities were sampled and households selected randomly within each community. Of 5862 couples (women aged 20 - 49 years) who were eligible for an interview, 5632 (96.07%) provided information in relation to all the questionnaire questions. The other couples did not participate because they were not at home for the interview, or became incapacitated, refused or others. The trained interviewers administered a detailed questionnaire to each study couple at their home, collecting the relevant information about contraception, sexual practices, marriage and a complete pregnancy history. The definition of infertility in the study was "a noncontracepting couple who want another child or a child if childless tried to conceive for at least 2 years" following the WHO recommendation([c2]). The study protocol was approved by the ethics committee of National Research Institute for Family Planning (NRIFP).
  
  
  RESULTS
  A total of 97 couples were classified as infertile. And the total prevalence of infertility in 7 Beijing districts was 1.72%. The standardized prevalence of infertility was 2.1%. 57 (58.76%) couples were classified as of primary infertility and 40 (41.24%) of secondary infertility. So the prevalence of primary and secondary infertilities were 1.01% and 0.71% respectively. In women, the prevalence of infertility was the highest in the age group of 20 - 29 (3.13%) and the lowest in the age group of 40 - 49 (1.38%). The prevalence rate of infertility in the women whose marriage age were younger than 20 years or elder than 29 years of age was apparently higher than those of the 20 - 29 years old. The risk factors of infertility were tuberculosis (TB), endometriosis (EM) and pelvic infection disease (PID).
  
  
  CONCLUSIONS
  The prevalence rate of infertility declines with age in women. Both EM and PID are the risk factors for infertility.
authors.affiliation: National Research Institute for Family Planning, Beijing 100081, China.
authors.forename: Yan-Qing
authors.initials: YQ
authors.lastname: Yang
authors.forename: He
authors.initials: H
authors.lastname: Shen
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Zhen-Wen
authors.initials: ZW
authors.lastname: Chen
mesh_terms: D000328:Adult; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004715:Endometriosis / Q000150:complications; D005260:Female; D006801:Humans; D007246:Infertility / Q000453:epidemiology* / Q000209:etiology; D008875:Middle Aged; D000292:Pelvic Inflammatory Disease / Q000150:complications; D015995:Prevalence; D012307:Risk Factors; D055815:Young Adult