Table 1 Summary of Exposure, Outcome and Other Background Confounding and Precision Measures

Exposure variable:

 Maternal alcohol use

Quantity and frequency of maternal alcohol use (standard drink = 10 g of alcohol).

1. Abstinent: no consumption;

2. Low: ≤7 standard drinks per week, up to 2 standard drinks per occasion;

3. Moderate: ≤7 standard drinks per week, > 2 to ≤4 standard drinks per occasion;

4. Binge: ≤7 standard drinks per week, > 4 standard drinks per occasion^a;

5. Heavy: > 7 standard drinks per week; at least weekly or more.

Mother (T1-T3)

O’Leary et al.’s (2010) Prenatal Alcohol Exposure (PAE) categories

Outcome variable:

 Infant Gross Motor (GM)

 Development

Example: Infant can sit upright unsupported.

Standardised GM scaled scores (mean = 10, SD = 3), adjusted for age and prematurity.

Infant (12 M)

Bayley Scales of Infant and Toddler Development - Third edition (BSID-III) [22]

Background confounder and precision variables:

 Age at birth

Calculated based on mother/partner and infant date of birth.

≤ 24 years; 25–29 years; 30–35 years; ≥ 36 years.

Mother, partner (T3/8W)

 Education

What is your highest level of education?

Less than Year 12; Year 12; Trade certificate, diploma or apprenticeship; Tertiary qualification.

Mother, partner (T3)

 Birth country

In which country were you born?

Australia; other English-speaking country; non-English-speaking country.

Mother, partner (T3)

 Single parent household

What is your current marital status?

Single parent household (Yes or No).

Mother (T3)

 Aboriginal and Torres Strait

 Islander status

Are you Aboriginal and/or Torres Strait Islander?

Yes or No.

Mother, partner (T3)

 First language spoken

What was your first language spoken?

English; Language other than English.

Mother, partner (T3)

 Socio-economic status (SES)

The Socio-Economic Indexes for Areas (SEIFA) data package was used to classify participants into low, moderate or high socio-economic status (SES) deciles based on residential postcode.

Low = deciles 1–3; Moderate = deciles 4–7; High = deciles 8–10.

Mother, partner (T3)

SEIFA data package [45]

 State of residence

State of residence in Australia

New South Wales (NSW) or Western Australia (WA).

Mother (T3)

 Tobacco in pregnancy

Tobacco use in pregnancy (ever used).

Yes or No.

Mother

(T1-T3), partner (T3)

 Illicit substance in pregnancy

Illicit substance use in pregnancy (ever used).

Yes or No.

Mother

(T1-T3), partner (T3)

 Maternal Depression

In the last 7 days …. I have felt sad or miserable.

Yes most of the time; Yes quite often; Not very often; No not at all. Coded as Normal (scores <9) or Elevated (scores ≤9).

Mother

(T1-T3), partner (T3)

Edinburgh Depression Scale (EDS) [26]

 Stress

Over the past week …. I found it hard to wind down.

Not at all; Some degree, or some of the time; Considerable degree, or a good part of the time; Very much, or most of the time. Coded as Normal (scores <10) or Elevated (scores ≤10).

Mother

(T1-T3), partner (T3)

Depression, Anxiety and Stress Scales [27]

 Anxiety

Over the past week …. I felt I was close to panic.

Not at all; Some degree, or some of the time; Considerable degree, or a good part of the time; Very much, or most of the time. Coded as Normal (scores <19) or Elevated (scores ≤19).

Mother

(T1-T3),

partner (T3)

Depression, Anxiety and Stress Scales [27]

 Victim of spousal abuse

My partner insults or shames me in front of others.

Never; Rarely; Occasionally; Frequently; Very Frequently Scores indicating at least moderate severity on the physical or non-physical subscales were combined then binary coded to indicate the presence or absence of abuse (Yes or No).

Mother, partner (T3)

The Index of Spousal Abuse [28]

 Estimated IQ

TOPF scores were converted to provide a valid predictor of the full-scale WAIS-IV IQ [46].

Low average = ≤84; Average = 85–99; High average = 100–114; Superior = ≥115.

Mother, partner (12 M)^b

Test of Premorbid Functioning (TOPF) [29]

 Parity

Total number of pregnancies carried to term prior to the current pregnancy [47].

0; 1–2; ≥3.

Mother (T3)

 Pre-pregnancy body mass

 index (BMI)

BMI was calculated based on self-reported pre-pregnancy weight and height [48].

Underweight = < 18.49; Normal weight = 18.50–24.99; Overweight = 25.00–29.99; Obese = ≥30.00 [49].

Mother, partner (T3)

 Pregnancy planning

How did you feel about becoming pregnant?

I wanted to become pregnant; I didn’t want to become pregnant; I hadn’t thought about becoming pregnant; Other. Responses were re-coded as pregnancy planned versus not planned; ‘other’ responses were classified based on examination of open-ended responses (n = 69).

Mother (T3)

 Partner alcohol use

Quantity and frequency of partner alcohol use (standard drink = 10 g of alcohol)

1. Abstinent: no consumption;

2. Low: ≤7 standard drinks per week, up to 2 standard drinks per occasion;

3. Moderate: < 14 standard drinks per week, > 2 to ≤4 standard drinks per occasion;

4. Binge: ≤14 standard drinks per week, > 4 standard drinks on one occasion;

5. Heavy: > 14 standard drinks per week; at least weekly consumption or more.

Partner (T3)

Australian NHMRC guidelines for drinking among non-pregnant adults were used to classify binge and heavy drinking [50]

 Infant sex

What gender is your baby?

Female; Male.

Mother (8 W)

Extracted from hospital records (Blue Books), as recorded by hospital staff at birth.

 Prematurity

Number of weeks gestation at birth.

Not premature = ≥37 weeks; Premature = ≤36 weeks.

Mother (8 W)

Extracted from hospital records (Blue Books), as recorded by hospital staff at birth.

 Birthweight

Weight in grams at birth, coded into two categories based on Australian norms [51].

Normal= > 10th percentile for gestational age; Small for gestational age (SGA) = ≤10th percentile for gestational age.

Mother (8 W)

Extracted from hospital records (Blue Books), as recorded by hospital staff at birth.

 Head circumference

Reported in centimetres.

Normal= > 3rd percentile; Small = ≤3rd percentile.

Mother (8 W)

Extracted from hospital records (Blue Books), as recorded by hospital staff at birth.

 Apgar score (5 min)

Post-birth measure of infant health.

Normal = ≥7; Problems at birth = < 7.

Mother (8 W)

Extracted from hospital records (Blue Books), as recorded by hospital staff at birth.