title: Vitamin D deficiency prevalence and risk factors among pregnant Chinese women.
abstract: OBJECTIVE
  To evaluate vitamin D deficiency prevalence and risk factors among pregnant Chinese women.
  
  
  METHODS
  A descriptive cross-sectional analysis.
  
  
  METHODS
  China National Nutrition and Health Survey (CNNHS) 2010-2013.
  
  
  METHODS
  A total of 1985 healthy pregnant women participated. Possible predictors of vitamin D deficiency were evaluated via multiple logistic regression analyses.
  
  
  RESULTS
  The median serum 25-hydroxyvitamin D level was 15·5 (interquartile range 11·9-20·0, range 3·0-51·5) ng/ml, with 74·9 (95 % CI 73·0, 76·7) % of participants being vitamin D deficient (25-hydroxyvitamin D <20 ng/ml). According to the multivariate logistic regression analyses, vitamin D deficiency was positively correlated with Hui ethnicity (P=0·016), lack of vitamin D supplement use (P=0·021) and low ambient UVB level (P<0·001). In the autumn months, vitamin D deficiency was related to Hui ethnicity (P=0·012) and low ambient UVB level (P<0·001). In the winter months, vitamin D deficiency was correlated with younger age (P=0·050), later gestational age (P=0·035), higher pre-pregnancy BMI (P=0·019), low ambient UVB level (P<0·001) and lack of vitamin D supplement use (P=0·007).
  
  
  CONCLUSIONS
  Vitamin D deficiency is prevalent among pregnant Chinese women. Residing in areas with low ambient UVB levels increases the risk of vitamin D deficiency, especially for women experiencing advanced stages of gestation, for younger pregnant women and for women of Hui ethnicity; therefore, vitamin D supplementation and sensible sun exposure should be encouraged, especially in the winter months. Further studies must determine optimal vitamin D intake and sun exposure levels for maintaining sufficient vitamin D levels in pregnant Chinese women.
authors.affiliation: 1Department of Trace Element Nutrition,National Institute of Nutrition and Health,Chinese Center for Disease Control and Prevention,Room 103,Nanwei Road No. 29,Xicheng District,Beijing 100050,People's Republic of China.
authors.forename: Chunfeng
authors.initials: C
authors.lastname: Yun
authors.affiliation: 1Department of Trace Element Nutrition,National Institute of Nutrition and Health,Chinese Center for Disease Control and Prevention,Room 103,Nanwei Road No. 29,Xicheng District,Beijing 100050,People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.affiliation: 2Department of Nutrition Surveillance,National Institute of Nutrition and Health,Chinese Center for Disease Control and Prevention,Beijing,People's Republic of China.
authors.forename: Yuna
authors.initials: Y
authors.lastname: He
authors.affiliation: 1Department of Trace Element Nutrition,National Institute of Nutrition and Health,Chinese Center for Disease Control and Prevention,Room 103,Nanwei Road No. 29,Xicheng District,Beijing 100050,People's Republic of China.
authors.forename: Deqian
authors.initials: D
authors.lastname: Mao
authors.affiliation: 1Department of Trace Element Nutrition,National Institute of Nutrition and Health,Chinese Center for Disease Control and Prevention,Room 103,Nanwei Road No. 29,Xicheng District,Beijing 100050,People's Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.affiliation: 1Department of Trace Element Nutrition,National Institute of Nutrition and Health,Chinese Center for Disease Control and Prevention,Room 103,Nanwei Road No. 29,Xicheng District,Beijing 100050,People's Republic of China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: 1Department of Trace Element Nutrition,National Institute of Nutrition and Health,Chinese Center for Disease Control and Prevention,Room 103,Nanwei Road No. 29,Xicheng District,Beijing 100050,People's Republic of China.
authors.forename: Chun
authors.initials: C
authors.lastname: Yang
authors.affiliation: 1Department of Trace Element Nutrition,National Institute of Nutrition and Health,Chinese Center for Disease Control and Prevention,Room 103,Nanwei Road No. 29,Xicheng District,Beijing 100050,People's Republic of China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Piao
authors.affiliation: 1Department of Trace Element Nutrition,National Institute of Nutrition and Health,Chinese Center for Disease Control and Prevention,Room 103,Nanwei Road No. 29,Xicheng District,Beijing 100050,People's Republic of China.
authors.forename: Xiaoguang
authors.initials: X
authors.lastname: Yang
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005006:Ethnicity / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood* / Q000453:epidemiology*; D012307:Risk Factors; D013472:Sunlight; D014808:Vitamin D Deficiency / Q000097:blood* / Q000453:epidemiology*; D055815:Young Adult
keywords: 25-Hydroxyvitamin D; China; Deficiency; Insufficiency; Pregnancy; Vitamin D