Table 1 Variables where harmonization was possible, across cohorts

Maternal behaviors and risk factors

 Alcohol use

  Alcohol consumption before pregnancy (yes/no)

-^f

X^g

-

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