title: Increasing trend of prevalence of infertility in Beijing.
abstract: BACKGROUND
  Infertility is one of the most important and underappreciated reproductive health problems in developing countries. However, epidemiological data in the Chinese population are still sparse. The aim of the present study was to determine the current prevalence and prevalence trend of infertility in Beijing, and to identify the risk factors associated with infertility.
  
  
  METHODS
  This cross-sectional study was conducted in Beijing in 2012. A stratified cluster sampling method was used to select 12 448 couples of whom the female partners were born between 1955 and 1985. All subjects were interviewed face to face. Infertility was defined as the failure to achieve a clinical pregnancy after 12 months of regular unprotected sexual intercourse.
  
  
  RESULTS
  Of the 12 448 couples, 12 342 (99.1%) answered the questions appropriately. The prevalence of infertility was 4.2% (3.1% as primary and 1.1% as secondary infertility). An increase in the prevalence of infertility according to the age of the female partner was found: 1.3% infertility for married females born in the 1950s and 11.4% for married females born in the 1980s. The increase was found in both urban and suburban areas. In addition, a Logistic regression showed that for the female partner, higher education levels, an older age at first marriage, adverse occupational conditions, mental labor and pre-pregnancy contraception after marriage were all significantly associated with a higher risk of infertility.
  
  
  CONCLUSIONS
  The prevalence of infertility has increased significantly among couples in Beijing, possibly because of an interaction among multiple factors.
authors.affiliation: Department of Reproduction, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing 100026, China.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Reproduction, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing 100026, China.
authors.forename: Shuyu
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Reproduction, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing 100026, China.
authors.forename: Songwen
authors.initials: S
authors.lastname: Zhang
authors.affiliation: School of Public Health, Peking University, Beijing 100083, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.affiliation: Department of Reproduction, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing 100026, China.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Deng
mesh_terms: D000328:Adult; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007246:Infertility / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors