Table 3.
Hazard ratios (HR) and 95% confidence intervals for asthma in relation to exposure to antibiotics in fetal life, overall and by trimester, in full cohort of children and for children with siblings
| Groups of antibiotics | All children* | Children with siblings | |||||
|---|---|---|---|---|---|---|---|
| Crude† HR (95% CI) | Adjusted‡§ HR (95% CI) | No of cases¶ | Crude HR (95% CI) | No of cases¶ | Adjusted§ HR (95% CI) | ||
| Any | |||||||
| Overall | 1.36 (1.32 to 1.39) | 1.28 (1.25 to 1.32) | 2799 | 1.00 (0.94 to 1.08) | 2523 | 0.99 (0.92 to 1.07) | |
| Trimester: | |||||||
| 1 | 1.35 (1.30 to 1.40) | 1.29 (1.23 to 1.34) | 1 081 | 1.07 (0.95 to 1.20) | 965 | 1.09 (0.97 to 1.23) | |
| 2 | 1.39 (1.34 to 1.44) | 1.30 (1.25 to 1.35) | 1 312 | 0.99 (0.90 to 1.10) | 1 171 | 0.97 (0.87 to 1.08) | |
| 3 | 1.33 (1.28 to 1.39) | 1.26 (1.21 to 1.31) | 1 913 | 0.95 (0.85 to1.06) | 1 078 | 0.95 (0.84 to 1.06) | |
| Airway | |||||||
| Overall | 1.41 (1.37 to 1.46) | 1.31 (1.27 to 1.35) | 1971 | 0.99 (0.91 to 1.07) | 1773 | 0.98 (0.90 to 1.07) | |
| Trimester: | |||||||
| 1 | 1.51 (1.43 to 1.58) | 1.40 (1.33 to 1.47) | 656 | 1.09 (0.94 to 1.26) | 588 | 1.11 (0.95 to 1.30) | |
| 2 | 1.45 (1.39 to 1.51) | 1.33 (1.27 to 1.39) | 863 | 0.97 (0.86 to 1.10) | 768 | 0.97 (0.85 to 1.11) | |
| 3 | 1.33 (1.27 to 1.39) | 1.24 (1.18 to 1.30) | 817 | 0.95 (0.83 to 1.09) | 738 | 0.96 (0.84 to 1.11) | |
| Urinary tract/skin | |||||||
| Overall | 1.25 (1.20 to 1.30) | 1.23 (1.18 to 1.28) | 1209 | 1.01 (0.91 to 1.12) | 1087 | 0.98 (0.88 to 1.10) | |
| Trimester: | |||||||
| 1 | 1.16 (1.09 to 1.23) | 1.15 (1.08 to 1.22) | 437 | 1.07 (0.90 to 1.28) | 391 | 1.10 (0.91 to 1.33) | |
| 2 | 1.30 (1.23 to 1.37) | 1.26 (1.19 to 1.33) | 544 | 0.99 (0.85 to 1.16) | 485 | 0.93 (0.78 to 1.10) | |
| 3 | 1.31 (1.24 to 1.39) | 1.28 (1.21 to 1.36) | 460 | 0.94 (0.79 to 1.12) | 415 | 0.92 (0.76 to 1.10) | |
*Excludes children born to mothers with prescriptions for antibiotics without license in Sweden during study period (n=9).
†23 900 000 person years and 29 745 events. Individuals with reported event before date of entry (birth) were excluded (n=8).
‡22 600 000 person years and 28 055 events.
§Adjusted for maternal smoking during pregnancy, parity, family situation (cohort and sibling analyses), and mother’s country of birth, parental education, maternal asthma (cohort analyses), and age as analysis time scale. Individuals with missing information on included variables excluded.
¶All families discordant on asthma are included in analyses, but only those also discordant on exposure contribute to estimates in table therefore number of cases is number of families with siblings discordant for both antibiotic exposure and asthma.