title: Tea drinking as a risk factor for neural tube defects in northern China.
abstract: BACKGROUND
  Tea catechins inhibit the activity of the enzyme dihydrofolate reductase, which catalyzes the inactive form of folate 7,8-dihydrofolate to the active form of folate 5,6,7,8-tetrahydrofolate. This inhibition leads to disturbance of the folate metabolic pathway and to lower bioavailability of folate to cells; therefore, it may increase the risk of neural tube defects (NTDs) in a developing embryo. We examined the association between tea drinking during the periconceptional period and the risk of NTDs.
  
  
  METHODS
  Cases were fetuses or neonates with an NTD as ascertained through a population-based surveillance system in 4 rural counties of Shanxi Province in northern China during 2002 through 2007. Controls were term infants without congenital malformations. Demographic, reproductive, and exposure data were obtained through a face-to-face interview.
  
  
  RESULTS
  A total of 631 NTD cases and 857 controls were included in the analysis. Compared with women who did not drink tea during the periconceptional period (487 cases and 688 controls), women who drank tea daily (20 cases and 9 controls) had a 3-fold increased risk (odds ratio = 3.1 [95% confidence interval = 1.4-7.0]) of having an NTD-affected pregnancy. The elevated risk associated with daily tea drinking remained after adjusting for maternal age, educational level, occupation, and periconceptional folic acid supplementation (3.4 [1.4-8.3]). The association was present for all 3 major subtypes of NTDs (ie, anencephaly, spina bifida, and encephalocele).
  
  
  CONCLUSIONS
  Daily tea drinking during the periconceptional period was associated with an elevated risk of NTDs in this Chinese population.
authors.affiliation: Institute of Reproductive and Child Health and Ministry of Health Reference Laboratory for Reproductive Health, Peking University Health Science Center, Haidian District, Beijing 100871, Beijing 100191, People’s Republic of China.
authors.forename: Rongwei
authors.initials: R
authors.lastname: Ye
authors.forename: Aiguo
authors.initials: A
authors.lastname: Ren
authors.forename: Le
authors.initials: L
authors.lastname: Zhang
authors.forename: Zhiwen
authors.initials: Z
authors.lastname: Li
authors.forename: Jianmeng
authors.initials: J
authors.lastname: Liu
authors.forename: Lijun
authors.initials: L
authors.lastname: Pei
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Zheng
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D019587:Dietary Supplements; D004327:Drinking Behavior; D005260:Female; D005492:Folic Acid; D006801:Humans; D007231:Infant, Newborn; D009436:Neural Tube Defects / Q000453:epidemiology*; D016017:Odds Ratio; D011159:Population Surveillance; D011247:Pregnancy; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013662:Tea / Q000009:adverse effects*
chemical_list: D013662:Tea; D005492:Folic Acid