TABLE 1.

Prevalence of offspring outcomes, paternal and maternal measures in 1,342 offspring of 1,122 mothers from two U.S. offspring of twins studies conducted in 2001 and 2004.

Measure	Abbreviation	%
Maternal smoking during pregnancy	MSDP	14.2
Self-reported whether they had smoked during the 1st, 2nd and the 3rd trimester of pregnancy.
Maternal drinking during pregnancy	MDDP	12.3
Self-reported whether they had consumed alcoholic beverages even on one day after knowing they were pregnant (during any pregnancy).
Maternal heavy smoking	MHSI	16.7
A score of 4 or more on the Heaviness of Smoking Inventory (H.S.I.) (Heatherton et al., 1989) indicating risk for nicotine dependence (Chabrol et al., 2005).
Maternal current smoking	MCUR	15.5
Self-reported smoking at time of interview.
Maternal lifetime drug use	MDRG	43.3
Self-reported use of cannabis, cocaine, stimulants, sedatives, opiates, heroin, psychedelics, inhalants or hallucinogens.
Maternal alcohol dependence	MAD	8.6
Meeting criteria for lifetime DSM-IV alcohol dependence based on self-reported symptoms
Maternal attention deficit hyperactivity disorder	MADHD	7.8
Self-reported meeting criteria for ADHD prior to age 7 years.
Maternal conduct problems	MCDP	22.8
Self-reported, endorsing one or more items from a conduct problems behavior checklist.
Paternal DSM-IIIR nicotine dependence	PND	47.4
Meeting criteria for nicotine dependence from self-reported symptoms.
Paternal alcohol dependence	PAD	Grp 1: 31.7, Grp 2: 11.6, Grp 3: 13.2
High-risk sampling.
Paternal drug dependence	PDD	Grp 1: 69.1, Grp 2: 5.4, Grp 3: 6.8
High-risk sampling.
Paternal current smoking	PCUR	24.6
Self-reported smoking at time of interview.
Paternal conduct disorder	PCD	9.4
Meeting criteria for DSM-IIIR conduct disorder based on self-reported symptoms.
Offspring birth weight	BW*	Mean: 121.9 ounces (SE 0.6) **
Maternal report of birth weight (in ounces).
Offspring premature birth	PREM	7.9
Maternal report that the offspring was born 3 or more weeks prior to their due date.
Offspring attention deficit hyperactivity disorder problem	ADHD	10.5
Maternal endorsement of 6 or more DSM-IV inattention or hyperactivity/impulsivity symptoms (with or without impairment).
Offspring conduct disorder (3+ symptoms)	CD	13.5
Self-report of 3 or more DSM-IV symptoms of conduct disorder.
Offspring regular smoking	REGSMK	18.5
Self-report of having smoked 21 or more cigarettes over the lifetime and smoking three or more times per week for a minimum of three weeks.
Offspring remediation/remedial classes	REM	20.3
Maternal report of offspring using a speech/language therapist or using remedial/special education.
Offspring low scholastic achievement	EDU	16.4
Self-report of consistently receiving C's or lower grades in school.

^*4.5% of the offspring had a birthweight that was less than 88 ounces (approximately 2496 grams).

^**121.9 ounces ≈ 3, 456 grams