Table 4.
Estimated difference in probability (percentage points) of childhood atopic medication purchases by birth order. Comparison of OLS models (M1–M4) and sibling fixed effects models (M5) with 95% confidence intervals. (Sibling-population N = 324,306)
| Birth order (ref. 1st) | Birth order (ref. 1st) | |||||
|---|---|---|---|---|---|---|
| 2nd | 3rd | 4th + | 2nd | 3rd | 4th + | |
| Antihistamines | Eczema medication | |||||
| M1a | -5.1 (-5.5; -4.7) | -10.7 (-11.3; -10.2) | -18.7 (-19.3; -18.1) | -2.4 (-2.8; -2.0) | -5.3 (-5.9; -4.8) | -9.3 (-9.8; -8.7) |
| M1b | -4.6 (-5.0; -4.2) | -6.9 (-7.5; -6.3) | -11.7 (-12.4; -11.0) | -2.0 (-2.4; -1.7) | -3.1 (-3.6; -2.5) | -5.3 (-6.0; -4.6) |
| M2 | -4.4 (-4.8; -4.0) | -6.6 (-7.2; -6.0) | -10.4 (-11.1; -9.7) | -1.9 (-2.3; -1.6) | -2.9 (-3.4; -2.3) | -4.7 (-5.4; -4.0) |
| M3 | -4.2 (-4.6; -3.8) | -6.4 (-6.9; -5.8) | -9.7 (-10.4; -9.0) | -1.7 (-2.1; -1.3) | -2.6 (-3.1; -2.0) | -4.0 (-4.7; -3.3) |
| M4 | -4.2 (-4.6; -3.8) | -6.4 (-6.9; -5.8) | -9.5 (-10.2; -8.8) | -1.7 (-2.1; -1.3) | -2.6 (-3.2; -2.1) | -4.1 (-4.8; -3.4) |
| M5 | -4.9 (-5.5; -4.4) | -7.8 (-8.8; -6.7) | -10.5 (-12.2; -8.8) | -1.6 (-2.1; -1.0) | -2.0 (-3.0; -0.9) | -2.4 (-4.1; -0.7) |
| Asthma medication | Epinephrine | |||||
| M1a | -1.4 (-1.8; -1.1) | -4.0 (-4.4; -3.6) | -6.3 (-6.7; -5.8) | -0.5 (-0.7; -0.4) | -1.2 (-1.3; -1.0) | -1.9 (-2.1; -1.8) |
| M1b | -1.2 (-1.6; -0.9) | -2.6 (-3.1; -2.2) | -4.0 (-4.5; -3.4) | -0.5 (-0.6; -0.4) | -0.9 (-1.1; -0.7) | -1.4 (-1.6; -1.2) |
| M2 | -1.2 (-1.5; -0.9) | -2.5 (-3.0; -2.0) | -3.6 (-4.1; -3.0) | -0.5 (-0.6; -0.3) | -0.9 (-1.1; -0.7) | -1.2 (-1.5; -1.0) |
| M3 | -1.1 (-1.4; -0.7) | -2.4 (-2.8; -1.9) | -3.2 (-3.7; -2.6) | -0.4 (-0.5; -0.2) | -0.8 (-1.0; -0.6) | -1.1 (-1.3; -0.8) |
| M4 | -1.0 (-1.4; -0.7) | -2.4 (-2.9; -1.9) | -3.1 (-3.7; -2.5) | -0.4 (-0.5; -0.2) | -0.8 (-1.0; -0.6) | -1.1 (-1.3; -0.8) |
| M5 | -0.5 (-1.0; -0.1) | -1.0 (-1.8; -0.2) | -1.5 (-2.8; -0.2) | -0.5 (-0.7; -0.3) | -1.1 (-1.4; -0.7) | -1.6 (-2.1; -1.0) |
Abbreviations; ref. = reference category
M1a adjusted for: child’s sex, birth year, and immigrant background. M1b: M1a + number of siblings. M2: M1 + region and urbanicity of residence
M3: M2 + household income and parental education. M4: M3 + mode of delivery and parental atopic medication purchases. M5: M4 + sibling fixed effects