Table 3
Prevalence odds ratio by maternal education level during 2009 to 2019

Unhealthy dietary habits Maternal education (reference: ≥college)	2009–2010 OR (95% CI)	2011–2013 OR (95% CI)	2014–2016 OR (95% CI)	2017–2019 OR (95% CI)	OR for time trend (2017–2019 relative to 2009–2010)
Insufficient consumption of fruit and vegetable
High school	1.41 (1.37–1.46)	1.38 (1.35–1.41)	1.41 (1.38–1.44)	1.41 (1.37–1.46)	1.28 (1.24–1.32)
≤Middle school	1.58 (1.49–1.68)	1.60 (1.52–1.67)	1.52 (1.43–1.63)	1.45 (1.30–1.62)	1.18 (1.04–1.33)
Insufficient consumption of milk
High school	1.21 (1.17–1.25)	1.21 (1.19–1.24)	1.18 (1.15–1.21)	1.12† (1.08–1.16)	1.24 (1.17–1.30)
≤Middle school	1.31 (1.23–1.39)	1.29 (1.23–1.36)	1.21 (1.13–1.30)	1.11* (0.98–1.25)	1.12 (0.98–1.29)
Skipping breakfast
High school	1.37 (1.32–1.42)	1.37 (1.34–1.41)	1.38 (1.35–1.41)	1.39 (1.35–1.42)	1.58 (1.53–1.64)
≤Middle school	1.83 (1.72–1.94)	1.60† (1.52–1.69)	1.55‡ (1.46–1.65)	1.61* (1.47–1.75)	1.38 (1.24–1.53)
Frequent consumption of fast food
High school	0.94 (0.90–0.98)	1.02† (0.99–1.05)	0.99* (0.96–1.02)	1.03‡ (1.00–1.06)	2.25 (2.16–2.33)
≤Middle school	1.10 (1.01–1.20)	1.10 (1.03–1.18)	0.99 (0.91–1.08)	1.00 (0.90–1.11)	1.86 (1.64–2.12)
Frequent consumption of soft drinks
High school	1.06 (1.02–1.10)	1.11 (1.08–1.13)	1.11* (1.09–1.14)	1.19‡ (1.16–1.23)	1.93 (1.87–2.00)
≤Middle school	1.22 (1.15–1.30)	1.28 (1.22–1.35)	1.16 (1.08–1.24)	1.20 (1.10–1.31)	1.68 (1.51–1.87)
Frequent consumption of instant noodles
High school	1.22 (1.18–1.26)	1.24 (1.21–1.27)	1.20 (1.16–1.24)	1.18 (1.13–1.23)	1.15 (1.10–1.21)
≤Middle school	1.49 (1.39–1.59)	1.49 (1.41–1.57)	1.39 (1.28–1.51)	1.21† (1.05–1.39)	0.97 (0.84–1.13)

All models include maternal education level, four periods, interaction term of maternal education level and four periods, sex, and grade.
CI, confidence interval; OR, odds ratio.
*P<0.05, ^†P<0.01, ^‡P<0.001 are for interaction between maternal educational level and each time period.