title: The Sex Ratio at Birth for 5,338,853 Deliveries in China from 2012 to 2015: A Facility-Based Study.
abstract: OBJECTIVE
  The accuracy of a population-based sex ratio at birth (SRB) in China has long been questioned. To depict a more accurate profile, the present study used data from a national surveillance system for health facility births to explore the characteristics of SRB in China.
  
  
  METHODS
  Data from China's National Maternal Near Miss Surveillance System between 2012 and 2015 were used. We restricted the analysis to live births of ≥28 completed gestational weeks or ≥1000 g birth weight. The strength of association between obstetric characteristics and SRB was examined using logistic regression, taking into account the sampling strategy and clustering of births within health facilities.
  
  
  RESULTS
  There were 2,785,513 boys and 2,549,269 girls born alive between 2012 and 2015 in 441 health facilities. The SRB was 111.04 in 2012, 110.16 in 2013, 108.79 in 2014, and 109.53 in 2015. The SRB was high in the eastern region, especially in rural areas. The SRBs increased with mother's age and decreased with mother's education. The SRB in women who were pregnant for the first time was 104.30. The SRB in primipara was normal (104.35), but it was extremely high in non-primipara, especially for women with three or more parities (141.76); only 5.26% of live births fell within this group. The SRBs increased significantly by the number of parities, especially in the rural areas of the central region. After adjustment for sociodemographic factors, women with three or more parities were 1.39 (95% CI 1.34, 1.43) times more likely to give birth to a boy compared with primiparae who were pregnant for the first time.
  
  
  CONCLUSIONS
  Our analysis suggests that the SRB was lower than what was reported officially but higher than normal. The government should keep strengthening supervision to prevent sex-selection, especially in the wake of the two-child policy implemented in 2015.
authors.affiliation: Nursing Department, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: National Office for Maternal and Child Health Surveillance of China, West China Second University Hospital, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Tang
authors.affiliation: National Office for Maternal and Child Health Surveillance of China, West China Second University Hospital, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Mu
authors.affiliation: National Office for Maternal and Child Health Surveillance of China, West China Second University Hospital, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Li
authors.affiliation: National Office for Maternal and Child Health Surveillance of China, West China Second University Hospital, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liu
authors.affiliation: National Office for Maternal and Child Health Surveillance of China, West China Second University Hospital, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Wang
authors.affiliation: National Office for Maternal and Child Health Surveillance of China, West China Second University Hospital, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Mingrong
authors.initials: M
authors.lastname: Li
authors.affiliation: National Office for Maternal and Child Health Surveillance of China, West China Second University Hospital, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Li
authors.affiliation: National Office for Maternal and Child Health Surveillance of China, West China Second University Hospital, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Li
authors.initials: L
authors.lastname: Dai
authors.affiliation: National Office for Maternal and Child Health Surveillance of China, West China Second University Hospital, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Liang
authors.affiliation: National Office for Maternal and Child Health Surveillance of China, West China Second University Hospital, Key Laboratory of Birth Defects and Related Diseases of Women and Children, Ministry of Education, Sichuan University, Chengdu, Sichuan, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
mesh_terms: D001723:Birth Rate; D002681:China; D005260:Female; D006268:Health Facilities / Q000706:statistics & numerical data; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D012042:Registries / Q000592:standards; D012744:Sex Ratio