Table 1.

Variables where harmonization was possible, across cohorts

Harmonized Variable		AOFa	APrONb	FAMILYc	OBSd	3De
Maternal behaviors and risk factors
Alcohol use
Alcohol consumption before pregnancy (yes/no)		-f	Xg	-	X	-
Alcohol consumption during year prior to pregnancy (yes/no)		X	-	X	X	X
Alcohol consumption during pregnancy (yes/no)		X	X	X	X	X
Binge drinking during year prior to pregnancy (yes/no)h		X	-	-	X	X
Binge drinking during pregnancy (yes/no)		X	-	X	X	X
Age
Age at first questionnaire response during current pregnancy (integer)		X	-	X	X	X
Age at delivery for current pregnancy/birth (integer)		X	X	X	-	X
Ethnicity
Ethnic background – White (yes/no)		X	X	X	X	X
Marital status
Marital status (categorical)		X	X	-	X	X
Education
Highest level of education completed (categorical)		X	X	-	X	X
Employment
Employment status (yes/no)		X	-	X	X	X
Income
Income level (categorical)		X	X	X	X	X
Smoking
Cigarette smoking before pregnancy (yes/no)		-	X	X	X	X
Cigarette smoking during pregnancy (yes/no)		X	X	X	X	X
Physical Measures
BMI before pregnancy (continuous)		X	X	X	X	X
Current Pregnancy
Maternal reproductive history
Gravidity (integer)		X	X	X	X	X
Previous live births (integer)		X	X	X	X	X
Maternal co-morbidities
Gestational hypertension (yes/no)		X	X	X	X	X
Gestational diabetes (yes/no)		X	X	X	X	X
Pre-eclampsia or eclampsia (yes/no)		X	X	X	X	-
Birth outcomesi
Live birth (yes/no)		X	X	X	X	X
Gestational age at delivery (integer)		X	X	X	X	X
Birth weight (yes/no)		X	X	X	X	X

^aAll Our Families

^bAlberta Pregnancy Outcomes and Nutrition

^cFamily Atherosclerosis Monitoring In earLY life

^dOntario Birth Study

^e3D Study—Design, Develop, Discover

^f-Variable not possible to harmonize

^g X Variable was harmonized

^h Binge drinking was defined as consuming 5 or more drinks on one occasion in AOF, APrON, FAMILY, and 3D, and as consuming 4 or more drinks on o ne occasion in OBS

ⁱ Birth outcomes focus on singleton births or the first of a multiple birth