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) | Â | 0 (0 to 14) | Â | 3 (0 to 15) | Â |
 | 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) | Â | 6 (0 to 49) | Â | 5 (1 to 23) | Â |
 | 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) | Â | 8 (0 to 81) | Â | 7 (2 to 37) | Â |
 | 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) | Â | 7 (0 to 61) | Â | 6 (1 to 30) | Â |
 | 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) | Â | 6 (0 to 60) | Â | 5 (1 to 28) | Â |
 | <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) | Â | 4 (0 to 54) | Â | 4 (0 to 24) | Â |
 | 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) | Â | 4 (0 to 46) | Â | 3 (0 to 21) | Â |
 | 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) |  |