Table 3.
Breastfeeding and children’s externalising behaviours at 9 and 13 years of age: pre- and post-matching results
| Up to 25 weeks | Pre matching | Post matching | ||||||
|---|---|---|---|---|---|---|---|---|
| T | C | Diff (sig.) | SE | T | C | Diff (sig.) | SE | |
| Conduct problems 9 years: maternal | 1.12 | 1.28 | − 0.16*** | 0.03 | 1.12 | 1.19 | − 0.06 | 0.07 |
| Hyperactivity 9 years: maternal | 2.73 | 3.07 | − 0.34*** | 0.06 | 2.73 | 2.94 | − 0.21 | 0.11 |
| Conduct problems 9 years: teacher | 0.55 | 0.65 | − 0.09** | 0.03 | 0.55 | 0.56 | − 0.01 | 0.06 |
| Hyperactivity 9 years: teacher | 1.96 | 2.30 | − 0.33*** | 0.07 | 1.96 | 2.12 | − 0.15 | 0.12 |
| Conduct problems 13 years: maternal | 0.99 | 1.07 | − 0.83* | 0.03 | 0.99 | 0.96 | 0.02 | 0.06 |
| Hyperactivity 13 years: maternal | 2.29 | 2.58 | − 0.28*** | 0.06 | 2.29 | 2.31 | − 0.01 | 0.11 |
| Between 26 and 50 weeks | ||||||||
| Conduct problems 9 years: maternal | 1.06 | 1.28 | − 0.22** | 0.07 | 1.06 | 1.26 | − 0.19 | 0.11 |
| Hyperactivity 9 years: maternal | 2.50 | 3.07 | − 0.57*** | 0.12 | 2.50 | 2.98 | − 0.48* | 0.19 |
| Conduct problems 9 years: teacher | 0.66 | 0.65 | 0.01 | 0.06 | 0.66 | 0.60 | 0.06 | 0.10 |
| Hyperactivity 9 years: Teacher | 1.80 | 2.30 | − 0.50*** | 0.13 | 1.80 | 2.31 | − 0.51* | 0.20 |
| Conduct problems 13 years | 1.02 | 1.07 | − 0.05 | 0.07 | 1.02 | 0.91 | 0.10 | 0.11 |
| Hyperactivity 13 years | 2.18 | 2.58 | − 0.39** | 0.12 | 2.18 | 2.26 | − 0.07 | 0.19 |
| 51 weeks or more | ||||||||
| Conduct problems 9 years: maternal | 0.92 | 1.28 | − 0.36*** | 0.09 | 0.92 | 1.18 | − 0.25 | 0.12 |
| Hyperactivity 9 years: maternal | 2.29 | 3.07 | − 0.78*** | 0.16 | 2.29 | 2.66 | − 0.36 | 0.22 |
| Conduct problems 9 years: teacher | 0.59 | 0.65 | − 0.06 | 0.09 | 0.59 | 0.52 | 0.07 | 0.13 |
| Hyperactivity 9 years: teacher | 2.10 | 2.30 | − 0.19 | 0.17 | 2.11 | 1.93 | 0.17 | 0.25 |
| Conduct problems 13 years | 0.94 | 1.07 | − 0.12 | 0.09 | 0.94 | 0.93 | 0.00 | 0.13 |
| Hyperactivity 13 years | 2.04 | 2.58 | − 0.53** | 0.16 | 2.05 | 2.04 | 0.00 | 0.22 |
T denotes ‘treatment’ (breastfed) and C denotes ‘control’ (not breastfed). ‘Diff’ represents the difference in scores between groups. SE refers to the standard errors. For being breastfed up to 25 weeks: N’s at age nine for the treatment group varied between 2458 and 2461 (teacher outcomes, 2369 and 2370) and the control group were between 2850 and 2852 (teacher outcomes, 2766). N’s at age 13 for the treatment group was 2239 and the control group was 2483. For being breastfed between 26 and 50 weeks: N’s at age nine for the treatment group varied between 460 and 461 (teacher outcomes, 445) and the control group varied between 2850 and 2852 (teacher outcomes, 2766). N’s at age 13 for the treatment group was 415 and 2483 for the control group. For being breastfed 51 weeks or more: N’s at age nine for the treatment group varied between 236 and 237 (teacher outcomes, 223) and the control group varied between 2850 and 2852 (teacher outcomes, 2766). N’s at age 13 for the treatment group was 204 and 2483 for the control group
*** Denotes significance at the p = < .001 level, ** at the .01 level, * at the .05 level, adjusted for multiple testing