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Table 4 Preterm delivery results for daily bottled, cold tap, total tap, and total water intake

From: The relationship between water intake and foetal growth and preterm delivery in a prospective cohort study

  Follow-up data Average of baseline
and follow-up data
Exposure n (%) Unadjusted RR (95% CI) Adjusted RR (95% CI)a Adjusted RR (95% CI)a
Bottled water     
   None 483 (25%) 1 1 1
   Any 1458 (75%) 1.2 (0.9, 1.8) 1.2 (0.8, 1.8) 0.8 (0.5, 1.4)
Cold tap water (ounces)b    
   0-27 472 (24%) 1 1 1
   > 27-53 494 (25%) 0.8 (0.5, 1.2) 0.8 (0.5, 1.3) 0.9 (0.6, 1.4)
   > 53-91 485 (25%) 0.9 (0.6, 1.3) 0.9 (0.6, 1.4) 0.9 (0.6, 1.4)
   > 91 490 (25%) 0.8 (0.5, 1.1) 0.8 (0.5, 1.3) 1.0 (0.6, 1.5)
Per 20 ounce 1.0 (0.9, 1.0) 0.9 (0.7, 1.3) 0.9 (0.6, 1.3)
Total tap water (ounces)b    
   0-30 493 (25%) 1 1 1
   > 30-61 483 (25%) 0.8 (0.5, 1.2) 0.8 (0.5, 1.2) 1.0 (0.6, 1.5)
   > 61-96 535 (28%) 0.7 (0.5, 1.1) 0.8 (0.5, 1.2) 1.2 (0.8, 1.9)
   > 96 429 (22%) 0.9 (0.6, 1.3) 1.0 (0.6, 1.5) 0.9 (0.6, 1.4)
Per 20 ounce 1.0 (0.9, 1.0) 0.9 (0.7, 1.2) 0.9 (0.6, 1.3)
Total water (ounces)b    
   0-51 491 (25%) 1.0 1.0 1.0
   > 51-78 478 (25%) 1.0 (0.7, 1.6) 1.2 (0.7, 1.9) 1.1 (0.7, 1.7)
   > 78-114 481 (25%) 1.0 (0.7, 1.6) 1.1 (0.7, 1.8) 1.0 (0.6, 1.5)
   > 114 478 (25%) 1.2 (0.8, 1.8) 1.4 (0.9, 2.2) 1.2 (0.8, 1.9)
Per 20 ounce 1.0 (1.0, 1.1) 1.1 (0.9, 1.4) 1.1 (0.8, 1.5)
  1. aAdjusted for race, education level, annual household income, smoking, pre-pregnancy BMI, vitamin use, parity, employed during last 4 months, infant gender, and study site
  2. bCategorical exposure cutpoints for average data results were slightly higher than the follow-up data
  3. BMI= body mass index; RR= risk ratio