Table 2 Association of daily toothbrushing frequency at 2 and 4 years postpartum with functional constipation.

From: Prospective association of daily toothbrushing frequency and the prevalence of childhood functional constipation: the Japan Environment and Children’s Study

Daily toothbrushing frequency at 2 years postpartum

Twice or more

Once

p-value

Less than once

p-value

Presence of constipation at 3 years of age, n (%)

4596 (11.5)

5432 (12.6)

 

95 (16.4)

 

  Crude

Ref

1.12 (1.07–1.17)

< 0.001

1.52 (1.20–1.92)

< 0.001

  Model 1a

1.11 (1.06–1.16)

< 0.001

1.55 (1.23–1.96)

< 0.001

  Model 2b

1.12 (1.07–1.17)

< 0.001

1.49 (1.17–1.88)

0.001

  Model 3c

1.12 (1.07–1.17)

< 0.001

1.46 (1.12–1.89)

0.005

Presence of constipation at 4 years of age, n (%)

3,843 (9.6)

4,886 (11.4)

 

91 (15.6)

 

  Crude

Ref

1.21 (1.16–1.27)

< 0.001

1.74 (1.37–2.22)

< 0.001

  Model 1a

1.18 (1.12–1.23)

< 0.001

1.71 (1.34–2.18)

< 0.001

  Model 2b

1.18 (1.13–1.24)

< 0.001

1.61 (1.26–2.06)

< 0.001

  Model 3c

1.18 (1.13–1.24)

< 0.001

1.38 (1.05–1.81)

0.020

Daily toothbrushing frequency at 4 years postpartum

Twice or more

Once

p-value

Less than once

p-value

Presence of constipation at 3 years of age, n (%)

7497 (11.8)

2587 (12.9)

 

39 (15.7)

 

  Crude

Ref

1.11 (1.05–1.17)

< 0.001

1.38 (0.93–2.07)

0.113

  Model 1a

1.11 (1.05–1.17)

< 0.001

1.42 (0.95–2.12)

0.086

  Model 2b

1.10 (1.05–1.16)

< 0.001

1.34 (0.89–2.00)

0.157

  Model 3c

1.10 (1.04–1.16)

< 0.001

1.30 (0.87–1.95)

0.196

Presence of constipation at 4 years of age, n (%)

6339 (10.0)

2432 (12.2)

 

49 (19.5)

 

  Crude

Ref

1.25 (1.18–1.31)

< 0.001

2.19 (1.57–3.04)

< 0.001

  Model 1a

1.22 (1.16–1.29)

< 0.001

2.16 (1.55–3.01)

< 0.001

  Model 2b

1.21 (1.15–1.28)

< 0.001

1.99 (1.43–2.77)

< 0.001

  Model 3c

1.21 (1.15–1.27)

< 0.001

1.87 (1.34–2.61)

< 0.001

  1. Odds ratio (95% confidence interval) (all such values).
  2. aAdjusted for maternal age, parity status, and child’s sex.
  3. bAdditionally adjusted for maternal (educational attainment, smoking, and drinking habit), and children’s factors (z-score of Kaup index at each time point, daily feeding frequency, and prevalence of congenital disease[s]), and household income with Model 1.
  4. cAdditionally adjusted for parental-supervised toothbrushing at each time point with Model 2.
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