Fig. 1

Subgroup analyses for the association between three dietary pattern scores (continuous, per 1-unit increase) and birth weight (continuous, in grams), stratified by maternal age, gestational periods, passive smoking, physical activity, and infant sex. Beta and 95% CI were calculated in linear model adjusted for maternal age (continuous variables, in years), and infant sex (male or female), maternal domicile place (south China, north China, or Shanghai surrounding area), pre-pregnancy BMI (< 18.5, 18.5–23.9, or ≥ 24.0 kg/m²), household income (< 100,000, 100,000-350,000, or ≥ 350,000 yuan/year), education (< 13 or ≥ 13 years), baseline season (spring/winter, summer, or autumn), parity (primiparous or multiparous), gestational periods at recruitment (first, second, or third trimester), passive smoking (yes or no), alcohol drinking (yes or no), multivitamin (yes or no), calcium tablets (yes or no), folic acid (yes or no), total energy (continuous variables, in kcal/day), gestational week at birth (continuous variables, in weeks), and the other two dietary scores. The corresponding stratification variable was excluded in the corresponding subgroup analysis, for example, infant sex was not adjusted in the analyses stratified by infant sex. N Total = number of total participants in the study. CI = confidence interval