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Table 1 Summary of risk factors, method and time of data collection and category level in analysis

From: The relationship between early life modifiable risk factors for childhood obesity, ethnicity and body mass index at age 3 years: findings from the Born in Bradford birth cohort study

Variable

Method and time of data collection

Category level in analysis

Pregnancy risk factors

 Maternal smoking during pregnancy

Self-report at 26–28 weeks gestation

No, Yes

 Gestational diabetes

Extracted from maternity notes

No, Yes

 Maternal booking BMI

Weight at booking from maternity notes, height measured at 26–28 weeks gestation

Underweight/normal (BMI ≤ 24.9)

Overweight (BMI 25–29.9)

Obese (BMI ≥ 30)

Postnatal risk factors

 Duration of any breastfeeding

Self-report at 6 and 12 months

Never, 1 day to <1 month, 1 to 4 months, 4+ months

 Age at weaning on to solids

Self-report at 6 and 12 months

≥17 weeks, <17 weeks

 Infant’s total energy intake per day

Food Frequency Questionnaire (FFQ) at 12 months

Kcals per day: continuous

 Infant’s total protein intake per day

FFQ at 12 months

Grams per day: continuous

 Caregivers feeding style

Questionnaire at 24 months

Authoritative, Authoritarian, Indulgent, Uninvolved

 Parenting style – Parental self-efficacy

Questionnaire at 24 months

High, lower scores (bottom quintile)

 Parenting style –Parental warmth

Questionnaire at 24 months

High, lower scores (bottom quintile)

 Parenting style – Parental hostility

Questionnaire at 24 months

Low, higher scores (top quintile)

 Infant TV viewing time

Questionnaire at 24 months

Hours per day: None, 0-1 hr, 1-2 hrs, 2+ hours

 Maternal TV viewing time

Questionnaire at 24 months

Hours per day: 0-2 hrs, 2-4 hrs, 4 + hrs

 Total infant sleep duration

Questionnaire at 24 months

Hours per day: <11 hrs, 11-12 hrs, 12-13 hrs, 13 + hrs

 Mothers physical activity

Questionnaire at 18 months

Sedentary (no activity), insufficiently active (<150 mins per week), sufficiently active (≥150 mins per week)