Table 1. Characteristics of the study population.

Child & family characteristics	N = 4,015	Percentages or means (sd)
Gender (% boys)		49.9%
Age at BPI¥ measurement in years		6.03 (0.35)
Child ethnicity
Dutch		67.4%
European		8.2%
Non-Western		24.4%
Number of children in the household		2.50 (1.72)
Age mother at intake		31.69 (4.54)
Age partner at intake		34.09 (5.28)
Harsh discipline by mother		2.18 (1.95)
Harsh discipline by father		1.82 (1.81)
Household income (% above modal)		68.7%
Marital status (% with partner)		92.8%
Highest educational level of parents
Low		4.4 %
Medium low		19.9 %
Medium high		26.5 %
High		49.3 %
Smoking during pregnancy
Never		79.3 %
Until pregnancy was known		9.1 %
Continued during pregnancy		11.6 %
Family functioning score		1.49 (0.41)
Psychopathology of mother score		3.43 (5.62)
Psychopathology of father score		2.71 (4.45)
Parent reported CBCL scores
Emotional problems score† at age 3		5.15 (4.39)
Behavioral problems score† at age 3		8.76 (5.71)
Emotional problems score† at age 6		5.44 (5.28)
Behavioral problems score† at age 6		6.94 (5.28)
Child self-reported BPI scores
Emotional problems score‡ at age 6		58.16 (12.10)
Behavioral problems score‡ at age 6		51.92 (10.60)

^†measured by the Child Behavior Checklist (parent report).

^‡measured by the Berkeley Puppet Interview (child self-report).