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

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)