title: [The trend of national advanced maternal age woman proportion in hospital-based surveillance].
abstract: OBJECTIVE
  To investigate the secular trend of advanced maternal age woman (>or= 35 year-old) in our country.
  
  
  METHODS
  Data on maternal woman at different age were collected at surveillance hospital in Chinese Birth Defects Monitoring Network from 1996 to 2007 and retrospective analysis of the trend of advanced maternal women were carried out. Trend analysis of the advanced maternal age in urban and rural areas of west, middle and east areas was also conducted. Chi-square test was applied to test the differences and the fitting model analysis was also applied.
  
  
  RESULTS
  A total of 6,308,594 parturient woman were monitored, included 354,511 woman (5.62%) of advanced maternal age. In 1996 and 2007, the proportion of the advanced maternal woman were 2.96% (12,508/422,486) and 8.56% (66,351/775,333), respectively. It showed an increasing trend for the national woman proportion of advanced maternal age from 1996 to 2007 (chi(2) = 45 376.16, P < 0.01). In city, the proportion of advanced maternal age woman were 2.95% (8755/296,975) and 7.69% (40,197/522,596) in 1996 and 2007, respectively. In rural region, the proportion of advanced maternal age woman were 2.99% (3753/125,511) and 10.35% (26,154/252,737) in 1996 and 2007, respectively. It showed increasing both in city and rural areas (chi(2)(city) = 24,152.86, P < 0.01; chi(2)(rural) = 20,809.79, P < 0.01). And the proportions in urban area and rural area were 5.13% (221,655/4,317,533) and 6.67% (132,856/1,991,061), the proportions difference was significant in statistics (chi(2) = 1536.260, P < 0.01). An Exponential model was established, ln(Y) = ln(2.52) + (0.103 x t). In east areas, the proportion were 3.90%and 8.81% in 1996 and 2007, respectively, in middle areas the respective proportions were 2.49% and 8.56%, in west areas were 2.11% and 8.21%. They all showed increasing trend in proportion of advanced maternal age from 1996 to 2007 year in east areas, middle areas and west areas (chi(2)(east) = 11,746.87, P < 0.01; chi(2)(middle) = 17,350.21, P < 0.01; chi(2)(west) = 16,432.68, P < 0.01). But the proportions of city and rural were different in those areas.
  
  
  CONCLUSIONS
  The proportion of advanced maternal woman had secular increasing trend and the rates were lower in city than in rural areas.
authors.affiliation: National Center for Birth Defects Monitoring, the West China Second Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Yue-hua
authors.initials: YH
authors.lastname: Li
authors.forename: Yan-ping
authors.initials: YP
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Dai
authors.forename: Guang-xuan
authors.initials: GX
authors.lastname: Zhou
authors.forename: Juan
authors.initials: J
authors.lastname: Liang
authors.forename: Qi
authors.initials: Q
authors.lastname: Li
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
mesh_terms: D000328:Adult; D017677:Age Distribution; D002681:China; D005260:Female; D006771:Hospitals, Maternity; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D011247:Pregnancy; D012189:Retrospective Studies; D012424:Rural Population; D014505:Urban Population