Change in the probability of low birth weight, with 95% CI (linear models)
| Model 1: unadjusted (child’s sex) | Model 2: model 1+child characteristics | Model 3: model 1+maternal characteristics | Model 4: model 1+household sociodemographic variables | Model 5: fully adjusted | Model 6: model 5+sibling fixed effects | |||||||
| β | 95% CI | β | 95% CI | β | 95% CI | β | 95% CI | β | 95% CI | β | 95% CI | |
| Paternal age ≤24 | 0.96 | (0.60 to 1.31) | 0.51 | (0.14 to 0.88) | 0.57 | (0.14 to 1.00) | 0.74 | (0.37 to 1.11) | 0.23 | (−0.20 to 0.67) | −0.11 | (−0.83 to 0.61) |
| Paternal age 25–29 | 0.14 | (−0.07 to 0.34) | −0.08 | (−0.29 to 0.13) | 0.10 | (−0.13 to 0.33) | 0.09 | (−0.12 to 0.29) | −0.06 | (−0.29 to 0.17) | −0.17 | (−0.56 to 0.22) |
| Paternal age 30–34 | 0.000 | 0.000 | 0.000 | 0.000 | 0.000 | 0.000 | ||||||
| Paternal age 35–39 | 0.25 | (−0.01 to 0.50) | 0.34 | (0.08 to 0.60) | 0.11 | (−0.17 to 0.39) | 0.24 | (−0.01 to 0.50) | 0.15 | (−0.13 to 0.42) | 0.10 | (−0.35 to 0.54) |
| Paternal age ≥40 | 0.91 | (0.48 to 1.35) | 1.02 | (0.58 to 1.46) | 0.62 | (0.13 to 1.11) | 0.88 | (0.44 to 1.31) | 0.61 | (0.12 to 1.09) | 0.36 | (−0.51 to 1.23) |
| Constant | 1.78 | (1.61 to 1.95) | 2.81 | (2.54 to 3.08) | 1.52 | (1.31 to 1.72) | 1.82 | (1.41 to 2.23) | 2.66 | (2.20 to 3.12) | 2.47 | (1.84 to 3.09) |
| Number of observations | 106 652 | 106 652 | 106 652 | 106 652 | 106 652 | 106 652 | ||||||
| Number of sibling groups | 45 537 | |||||||||||
Model 1 adjusted for the child’s sex. Model 2 adjusted for the child’s birth order and birth year. Model 3 adjusted for maternal age and maternal smoking during pregnancy. Model 4 adjusted for household income deciles and household level of education. Model 5 is fully adjusted. Model 6 adjusted for all covariates in model 5 except household level of education since there was little variation between siblings. SEs are clustered at the family level.