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Table 2 Associations between tea consumption and risk of preterm birth (n = 10 179), Urban China, 2010–2012

From: Maternal tea consumption and the risk of preterm delivery in urban China: a birth cohort study

Drink tea Term (n) Preterm (n = 1019) Moderate preterm (n = 833) Very preterm (n = 186) Medically indicated (n = 338) Spontaneous (n = 681)
No. OR(95 % CI) No. OR(95 % CI) No. OR(95 % CI) No. OR(95 % CI) No. OR(95 % CI)
Never 8403 900 1 733 1 167 1 295 1 605 1
Ever 757 119 1.36(1.09–1.69) 100 1.41(1.12–1.79) 19 1.05(0.64–1.72) 43 1.24(0.85–1.83) 76 1.41(1.09–1.83)
 Before pregnancy 680 107 1.39(1.10–1.75) 91 1.47(1.15–1.87) 16 1.01(0.59–1.73) 36 1.24(0.82–1.88) 71 1.49(1.14–1.94)
 During pregnancy ever 377 69 1.38(1.04–1.83) 55 1.37(1.00–1.87) 14 1.34(0.75–2.39) 33 1.76(1.13–2.76) 36 1.19(0.83–1.72)
 Before pregnancy only 380 50 1.33(0.97–1.83) 45 1.47(1.05–2.05) 5 0.66(0.27–1.65) 10 0.62(0.30–1.28) 40 1.67(1.18–2.36)
 Before and during pregnancy 300 57 1.45(1.06–1.98) 46 1.47(1.05–2.06) 11 1.35(0.71–2.58) 26 1.92(1.17–3.15) 31 1.29(0.87–1.92)
 During pregnancy only 77 12 1.10(0.57–2.14) 9 1.01(0.48–2.13) 3 1.30(0.38–4.42) 7 1.25(0.48–3.28) 5 0.78(0.30–2.03)
  1. Adjusted for maternal age, educational level, employ status during pregnancy, monthly family income, parity, hypertensive disorder during pregnancy, prepregnancy BMI, alcohol drinking and smoking (active and passive smoking) during pregnancy and history of preterm
  2. Abbreviation: BMI body mass index