摘要目的：了解中国部分地区初产妇和经产妇阴道助产分娩率的变化趋势。方法1993至2010年在浙江、江苏及河北26县（市）监测单胎孕妇1569381万名。孕妇基本信息和分娩资料源自监测记录。阴道助产术包括胎头吸引、产钳助产、臀助产和臀牵引。采用趋势卡方检验评价阴道助产分娩率的时间变化趋势。结果共监测初产妇1317771名，阴道助产分娩78327名（5．9％）；经产妇251610名，阴道助产分娩8702名（3．5％）。2006至2010年初产妇和经产妇阴道助产分娩率分别为0．8％（691／84714）和0．6％（116／20280），1993至1995年分别为10．6％（38536／364503）和5．9％（4085／69099），前者仅是后者的7．5％和10．0％。按地区、城乡、医院级别及孕妇若干特征分层分析均获一致结果，即2006至2010年阴道助产分娩率显著低于18年前水平。结论18年间中国部分地区初产妇和经产妇阴道助产分娩率显著下降，目前居世界最低水平。我国已出台相关政策促进阴道分娩，预期阴道助产分娩率会合理回升，相关部门宜有所准备。

abstractsObjective To explore the secular trends of operative vaginal delivery ( OVD ) among nulliparous and multiparous women in southern and northern China.Methods A population-based perinatal healthcare surveillance system has been established in 26 counties/cities in Zhejiang, Jiangsu and Hebei provinces since 1993.A total of 1 569 381 singleton pregnant women were registered during 1993 -2010.Information concerning demographic characteristics and delivery mode was from surveillance records.OVD includes vacuum, forceps, assisted breech and breech extraction.Trend Chi-square test was performed to test the trends in OVD prevalence rate with the calendar years.Results 78 327 OVDs were identified among 1 317 771 nulliparous women and 8 702 among 251 610 multiparous women respectively.The OVD prevalence rate was 5.9% in nulliparous women and 3.5% in multiparous women.The OVD prevalence rate decreased remarkably by 92.5%from 10.6% ( 38 536/364 503 ) during 1993-1995 to 0.8%(691/84 714) during 2006-2010 in nulliparous women and by 90.0% from 5.9%(4 085/69 099) to 0.6% (116/20 280) in multiparous women.Moreover,stratified analyses consistently showed a decreasing trend in the OVD prevalence rate during the 18-year period regardless of living locations,delivery hospitals or demographic characteristics.In nulliparous women, the OVD prevalence rate decreased from 9.4%(5 271/56 163) during 1993-1995 to 1.4%(157/11 030) during 2006-2010 in southern urban area,from 11.8% (32 361/273 274) to 1.4% (402/29 069) in southern rural area and from 2.6% ( 904/35 066 ) to 0.3% ( 132/44 615 ) in northern rural area, and decreased from 8.6%(5 506/63 796) to 1.3%(208/16 408) at provincial hospitals,from 10.8%(13 659/126 529) to 0.7%(381/55 100) at county hospitals and from 12.1%(19 054/157 439) to 0.8%(100/12 959) at township hospitals.And similar results were further observed in different subgroups stratified by demographic characteristics.In multiparous women,a decreasing trend in OVD prevalence rate during the 18-year period was re-identified in various subgroups.Conclusion The OVD prevalence rate in both nulliparous and <br> multiparous women dramatically decreased in China during 1993-2010 and ranked the lowest in the world by 2010.Thus the relevant government departments should be prepared for the expected rebound in the occurrence of OVD given the national health policies of promoting vaginal deliveries.