Table 1 Definitions of variables used

Time-invariant

Wave 1 (children in 12 months)

Children gender

Male = 1, female = 2

Family member number

Continuous

Pregnant weight (kg)

Continuous

Physical activity in pregnant period (minutes/day)

Continuous

Pregnancy exercise

Yes = 1, no = 2

Pregnancy exercise intensity

Low intensity exercise = 1, moderate exercise = 2

Mother physical activity behavior

Yes = 1, no = 2

Mother physical activity

Low intensity exercise = 1, moderate exercise = 2, heavy exercise = 3

Pregnancy computer use

Yes = 1, no = 2

Pregnancy phone use

Yes = 1, no = 2

Maternal race (Han)

Ethnic Han = 1, not Ethnic Han = 2

Maternal age

Continuous

Educational level

Less than primary school = 1, middle school = 2, high school = 3, university = 4, graduate school = 5, other education = 6

Maternal occupation

Complete collection of Chinese Occupational Classification: class 1 = 1, class 2 = 2, class 3 = 3, class 4 = 4, class 5 = 5, class 6 = 6

Paternal race (Han)

Ethnic Han = 1, not Ethnic Han = 2

Paternal age

Continuous

Educational level

Less than primary school = 1, middle school = 2, high school = 3, university = 4, graduate school = 5, other education = 6

Paternal occupation

Complete collection of Chinese Occupational Classification: class 1 = 1, class 2 = 2, class 3 = 3, class 4 = 4, class 5 = 5, class 6 = 6

Infant weight (kg)

Continuous

Household income (yuan/month)

Less than 2000 yuan/month = 1, 2001–5000 yuan/month = 2, 5001–10,000 yuan/month = 3, 10,001–15,000 yuan/month = 4, More than 15,000 yuan/month = 5

Pregnancy depression

Not depression = 0, depression = 1

Time-variant

Wave 1–8 (from children in 12 months to 60 months)

Children’s daily screen time

Continuous

Children’s daily screen time prevalence

Accept AAP guideline (the reported amount of screen use among children was no more than the recommended screen time of AAP guidelines) = 0, exceed AAP guideline (the reported amount of screen use among children was more than the recommended screen time of AAP guidelines) = 1

Prevalence of children’s interest in screen use

No = 1, occasionally = 2, sometimes = 3, often = 4, always = 5

Children’s daily outdoor activity time

Continuous