2.3 Exposure assessment
The interview questionnaire contained items about physical exercise
during pregnancy and each
trimester, refers to the 1st
trimester (0 to 12 weeks of gestation), the 2nd trimester (13 to 28
weeks of gestation), and the 3rd trimester (after 28 weeks of
gestation). There were some questions about exercise on the
questionnaire: 1) “Have you exercised during pregnancy? The exercise
means any planned, organized, and repetitive physical activity.” 2)
“What is your primary exercise patterns (walking, brisk walking,
yoga/Pilates/maternity gymnastics, swimming, squat and others) during
pregnancy?” For each trimester, take the 1st trimester as an example,
3) “How many times do you exercise per week during the 1st trimester?”
4) “How many hours do you exercise at a time?”.
Since Chinese pregnancy health guidelines do not involve exercise during
pregnancy, the subjects’ activity was grouped according to the previous
studies and existing guidelines[8-9,12]. Time
spent on exercise were grouped as none and low (0-2.49h/week), moderate
(2.5-7h/week), and high
(>7h/week)[13]. One study defined
“moderate exercise” as that requiring 4.5 METs (Metabolic Equivalent
of Energy)[14]. So, energy expenditures were
grouped as none and low (0-11.24 MET.h/week), moderate (11.25-31.5
MET.h/week), and high (>31.5 MET.h/week). The calculation
of energy expenditure was based on the previous
criterion[14].