Table 1.

Data Sources, Descriptions and Definitions by Country

	Australia	Finland	Norway	Sweden
General population
Data source	National Drug Strategy Household Survey	Health Behavior and Health among the Finnish Adult Population Survey	Holiday and Travel Survey	National Public Health Survey
Main mode of data collection	Drop-and-collect questionnaire/ telephone interview	Postal questionnaire	Telephone interviews	Postal questionnaire
Start and frequency	Every 2–3 y since 1985	Annual since 1978	Quarterly since 1973	Annual since 2004
Data sets in this study	2001, 2004, 2007, 2010, 2013	1995–2014	1995–2014	2004–2015
Population	Women aged 16–44	Women aged 15–44	Women aged 16–44	Women aged 16–44
Sample	N = 5761–8130	Subset of total N = 2545–3644	N = 1079–1576	N = 1340–2837
Age groups reported	16–29 y	15–24 y	16–24 y	16–29 y
	30–44 y	25–44 y	35–44 y	30–44 y
Definition of smoker	Daily smoking	Daily smoking	Daily smoking	Daily smoking
Pregnant women
Data source	National Drug Strategy Household Survey	Medical Birth Registry	Medical Birth Registry	Medical Birth Registry
Main mode of data collection	Drop-and-collect questionnaire/ telephone interview	Medical records	Medical records	Medical records
Start and frequency	Every 2–3 y since 1985	Annual data since 1987	Annual data since 1973	Annual data since 1973
Data sets in this study	2001, 2004, 2007, 2010, 2013	1995–2014	1999–2014a	2000–2014a
Population	Women who were pregnant at time of survey	All children with birth weight >500 grams after week 22	All births after week 12	All births
Sample	N = 898, 888, 652, 817, 873	Whole population	Whole population	Whole population
Age groups reported	16–29 y	<20 y	<20 y	<20 y
	30–44 y	0–24 y	20–24 y	20–24 y
		25–29 y	25–29 y	25–29 y
		30–39 y	30–34 y	30–39 y
			35–39 y
Definition of smoker	Reported any smoking after knowledge of pregnancy	Continued smoking after first trimester	Smoking “at the end of the pregnancy”b	Smoking in week 30–32 of pregnancy

^aMaternal smoking habits recorded since 1999.

^bSmoking habits are only recorded if the mother consents. Data was available for 80%–88% of the pregnancies.