Table 4 Relationship between duration of breastfeeding and the prevalence of overweight and obesity amnog boys (aged 6 to 16 years) in Shibei District of Qingdao, China

6–8 years

Continuous

419

0.991(0.971,1.012)

0.990(0.970,1.011)

675

0.991(0.973,1.008)

0.98(0.971,1.007)

Categorical

 < 12 months

160

ref

ref

263

ref

ref

≧12momths

259

0.953(0.761,1.194)

0.948(0.756,1.189)

412

0.923(0.764,1.114)

0.89(0.740,1.085)

9–11 years

Continuous

398

0.991(0.969,1.014)

0.993(0.970,1.016)

525

0.974(0.954,0.994)*

0.97(0.958,0.999)*

Categorical

 < 12 months

172

ref

ref

248

ref

ref

≧12momths

226

0.868(0.688,1.095)

0.875(0.691,1.108)

277

0.738(0.598,0.910)*

0.787(0.653,0.975)*

≧12 years

Continuous

213

1.007(0.973,1.041)

1.009(0.974,1.044)

180

0.997(0.962,1.033)

0.999(0.964,1.035)

Categorical

 < 12 months

98

ref

ref

86

ref

ref

≧12momths

115

1.006(0.727,1.392)

1.009(0.727,1.400)

94

0.937(0.664,1.322)

0.921(0.650,1.306)