Table 1.

Inter-correlations between mother-rated study variables, means and standard deviations

	Breastfeeding	Maternal smoking	Maternal antisocial	Maternal education	Birth weight	Multiple birth	SCBU	Child age	Child sex	Conduct problems
1. Breastfeeding (No = 0 or Yes = 1)	–
2. Maternal smoking in pregnancy (No = 0 or Yes = 1)	−0.16**	–
3. Maternal antisocial behaviour	0.01	0.01	–
4. Maternal education	0.20**	−0.12**	−0.03	–
5. Birth weight (g)	0.11**	−0.11**	0.04	0.05	–
6. Multiple birth (No = 0 or Yes = 1)	−0.14**	−0.02	0.01	0.01	−0.52**	–
7. Special care baby unit (No = 0 or Yes = 1)	−0.05	0.03	−0.01	0.05	−0.51**	0.30**	–
8. Child age	0.00	0.06	0.01	0.00	−0.03	−0.02	0.01	–
9. Child sex (0 = female, 1 = male)	−0.03	0.03	−0.01	−0.01	0.03	0.03	0.07*	0.04	–
10. Conduct problems (mother rated)	−0.13**	0.08*	0.31**	−0.14**	−0.07	0.10**	0.10*	−0.07*	−0.08*	–
Mean (or median in italics)	1.00	0.00	3.90	1.84	3,088.39	0.00	0.00	6.25	1.00	1.51
Standard deviation	0.44	0.22	3.49	1.25	695.85	0.42	0.40	1.26	0.50	1.42

N = 870

* p < 0.05

** p < 0.01