Table 1.

The Observed Association of First Pregnancy with Registration for Drug Abuse in the General Population, in Cousin and Sibling Pairs Discordant for Pregnancy and Within-Individuals

	N	Frequency of Drug Abuse Registration		Odds Ratio and 95% Confidence Intervals				Cohen’s d# and 95% Confidence Intervals
		Pregnancy	Control	Model 1*		Model 2**		Model 1*
Population	149,512	0.24%	0.35%	0.67	0.60; 0.74	0.41	0.37; 0.46	0.22	0.17; 0.28
Cousins	50,371	0.23%	0.46%	0.49	0.39; 0.62	0.33	0.26; 0.42	0.39	0.26; 0.52
Siblings	19,115	0.20%	0.56%	0.35	0.24; 0.51			0.58	0.37; 0.79
Within Individual	150,226	0.24%	0.63%	0.22	0.19; 0.26			0.83	0.74; 0.92
Within Individual (2)1	150,226	0.24%	0.61%	0.25	0.21; 0.29			0.76	0.68; 0.86
Within Individual (3)2	150,226	0.24%	0.61%	0.26	0.22; 0.31			0.74	0.64; 0.83
Within Individual (2nd pregnancy)	75,891	0.11%	0.27%	0.23	0.16; 0.33			0.81	0.61; 1.01

^*Unadjusted

^**Adjusted for, Mean Parental Education and School Achievement

¹Control period ends 6 months prior to start of pregnancy

²Control period ends 12 months prior to start of pregnancy

^#(40)