Change in the probability of preterm delivery, 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 | 0.70 | (0.26 to 1.13) | 0.16 | (−0.29 to 0.61) | 0.21 | (−0.33 to 0.74) | 0.51 | (0.06 to 0.96) | −0.19 | (−0.74 to 0.35) | −0.45 | (−1.37 to 0.46) |
| Paternal age 25–29 | 0.23 | (−0.04 to 0.50) | −0.04 | (−0.32 to 0.23) | 0.1 | (−0.20 to 0.40) | 0.17 | (−0.10 to 0.45) | −0.1 | (−0.40 to 0.21) | 0.01 | (−0.48 to 0.50) |
| Paternal age 30–34 | 0.000 | 0.000 | 0.000 | 0.000 | ||||||||
| Paternal age 35–39 | 0.37 | (0.03 to 0.71) | 0.5 | (0.16 to 0.84) | 0.25 | (−0.11 to 0.62) | 0.38 | (0.04 to 0.71) | 0.31 | (−0.06 to 0.67) | 0.41 | (−0.16 to 0.97) |
| Paternal age ≥40 | 1.19 | (0.64 to 1.74) | 1.32 | (0.77 to 1.88) | 0.79 | (0.18 to 1.40) | 1.17 | (0.63 to 1.72) | 0.79 | (0.18 to 1.40) | 0.67 | (−0.42 to 1.77) |
| Constant | 3.62 | (3.39 to 3.84) | 4.8 | (4.45 to 5.15) | 3.5 | (3.22 to 3.78) | 3.59 | (3.05 to 4.13) | 4.67 | (4.05 to 5.30) | 3.83 | (3.04 to 4.62) |
| Number of observations | 106 652 | 106 652 | 106 652 | 106 652 | 106 652 | 106 652 | ||||||
| Number of siblings | 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.