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Table 2 Caffeine intake according to maternal characteristics

From: Maternal caffeine intake during pregnancy is associated with birth weight but not with gestational length: results from a large prospective observational cohort study

Characteristic Category n % Total caffeine, mg/day Coffee caffeine, mg/day Tea caffeine, mg/day
     Median (IQR) Pvaluea Median (IQR) Pvaluea Median (IQR) Pvaluea
Total - 59,123 100 57 (23 to 121) - 7 (0 to 69) - 5 (1 to 29) -
Maternal age, years <25 6,688 11 34 (15 to 81)   0 (0 to 14)   3 (0 to 15)  
  25 to 29 20,354 34 47 (19 to 102) <10-246 5 (0 to 46) <10-246 5 (1 to 22) <10-246
  30 to 34 25,213 43 68 (27 to 134)   11 (0 to 83)   6 (1 to 34)  
  >34 6,868 12 91 (39 to 171)   30 (1 to 124)   7 (2 to 38)  
Parity 0 30,393 51 47 (19 to 103)   6 (0 to 49)   5 (1 to 23)  
  1 18,686 32 66 (26 to 133) <10-92 8 (0 to 81) <10-92 6 (1 to 32) <10-36
  2 8,135 14 82 (31 to 163)   12 (0 to 101)   6 (1 to 35)  
  ≥3 1,873 3 94 (34 to 181)   17 (0 to 138)   5 (0 to 34)  
  Missing 36 0.1 58 (22 to 142) - 8 (0 to 98) - 7 (0 to 30) -
Marital statusb Yes 56,941 96 57 (23 to 120) 0.004 7 (0 to 69) 0.89 5 (1 to 29) <10-13
  No 2,182 4 60 (21 to 146)   6 (0 to 79)   3 (0 to 20)  
Pre-pregnancy BMI, kg/m2 <18.5 1,835 3 69 (27 to 145)   8 (0 to 81)   7 (2 to 37)  
  18.5 to 24.9 39,834 67 62 (25 to 129) <10-183 9 (0 to 79) <10-119 6 (1 to 33) <10-237
  25 to 29.9 12,444 21 51 (20 to 107)   5 (0 to 58)   5 (1 to 24)  
  ≥30 5,01 8 39 (14 to 84)   2 (0 to 32)   2 (0 to 13)  
Maternal education, years ≤12 17,925 30 55 (21 to 128)   4 (0 to 66)   3 (0 to 19)  
  13 to 16 24,782 42 54 (22 to 114) <10-34 7 (0 to 64) <10-124 6 (1 to 29) <10-276
  ≥17 15,201 26 65 (27 to 125)   14 (0 to 79)   7 (2 to 37)  
  Missing 1,215 2 60 (22 to 124) - 7 (0 to 69) - 5 (0 to 28) -
History of preterm delivery No 57,121 97 57 (22 to 121) <10-6 7 (0 to 68) 0.91 5 (1 to 29) 0.29
  Yes 1,928 3 69 (25 to 141)   7 (0 to 80)   6 (1 to 32)  
  Missing 74 0.1 47 (19 to 102) - 12 (0 to 84) - 5 (1 to 22) -
Smoking habits Never 54,136 92 54 (21 to 113)   7 (0 to 61)   6 (1 to 30)  
  Occasionally 1,569 3 109 (42 to 201) <10-226 44 (0 to 163) <10-226 3 (0 to 21) <10-101
  Daily 3,085 5 143 (57 to 260)   70 (0 to 198)   2 (0 to 14)  
  Missing 333 1 69 (24 to 127) - 10 (0 to 79) - 6 (0 to 34) -
Passive smoking No 51,931 88 56 (22 to 118) <10-24 7 (0 to 67) 0.08 6 (1 to 30) <10-53
  Yes 6,082 10 66 (24 to 153)   7 (0 to 86)   3 (0 to 19)  
  Missing 1,11 2 61 (22 to 139) - 7 (0 to 84) - 5 (0 to 26) -
Nicotine other than cigarettes No 58,552 99 57 (22 to 120) <10-52 7 (0 to 68) <10-49 5 (1 to 29) 0.06
  Yes 571 1 138 (57 to 221)   89 (4 to 178)   4 (0 to 27)  
Alcohol consumption, units/week No alcohol 52,47 89 53 (21 to 114)   6 (0 to 60)   5 (1 to 28)  
  <0.5 5,579 9 93 (44 to 168) <10-90 39 (4 to 118) <10-90 8 (2 to 37) <10-90
  ≥0.5 1,074 2 126 (67 to 216)   73 (13 to 173)   15 (2 to 39)  
Nausea during second trimester No 52,567 89 59 (24 to 125) <10-83 8 (0 to 74) <10-167 5 (1 to 29) <10-10
  Yes 6,556 11 43 (16 to 97)   0 (0 to 21)   4 (0 to 28)  
Partners with income of >300,000 NOK/year 0 16,327 28 49 (19 to 113)   4 (0 to 54)   4 (0 to 24)  
  1 24,483 41 56 (22 to 120) <10-72 6 (0 to 66) <10-152 5 (1 to 28) <10-81
  2 16,746 28 68 (28 to 129)   14 (0 to 83)   6 (2 to 34)  
  Missing 1,567 3 57 (21 to 131) - 5 (0 to 65) - 4 (0 to 24) -
Baby's sex Male 30,049 51 58 (23 to 122) 0.13 7 (0 to 70) 0.7 5 (1 to 29) 0.62
  Female 29,074 49 57 (22 to 120)   7 (0 to 68)   5 (1 to 29)  
Quartiles of energy intake, MJ <7.90 14,781 25 42 (15 to 96)   4 (0 to 46)   3 (0 to 21)  
  7.90 to 9.35 14,78 25 53 (21 to 112) <10-72 7 (0 to 66) <10-75 5 (1 to 28) <10-99
  9.36 to 11.14 14,782 25 61 (25 to 126)   8 (0 to 73)   6 (1 to 31)  
  >11.14 14,78 25 78 (32 to 158)   10 (0 to 89)   6 (1 to 44)  
  1. Caffeine intake (food frequency questionnaire data) according to maternal characteristics, n = 59,123, in the Norwegian Mother and Child Cohort Study 2002 to 2009.
  2. a P value for being sampled from the same distribution (Kruskal-Wallis test).
  3. cMarital status was defined as either married/cohabiting or not.
  4. BMI = body mass index.