Table 1.

Relation of duration of breast feeding to mean body mass index (BMI) and odds ratio for obesity^* in children aged 4-18 years in 1991

			Odds ratio (95% CI)
Duration of breastfeeding	No	Mean SD score for BMI (95% CI)	Adjusted for sex	Adjusted for confounders†
Children aged 4-8:	1541
<1 week	505	0.21 (0.11 to 0.31)	1.00	1.00
1 week to 1 month	215	0.27 (0.10 to 0.44)	1.19 (0.68 to 2.09)	1.04 (0.57 to 1.90)
2-3 months	220	0.12 (−0.02 to 0.26)	0.64 (0.33 to 1.25)	0.68 (0.34 to 1.35)
4-6 months	210	0.22 (0.07 to 0.37)	0.91 (0.49 to 1.68)	0.94 (0.50 to 1.78)
7-9 months	197	0.24 (0.09 to 0.39)	1.05 (0.58 to 1.92)	1.14 (0.61 to 2.16)
>9 months	194	0.19 (0.06 to 0.32)	0.54 (0.26 to 1.15)	0.61 (0.28 to 1.32)
Children aged 9-18:	1090
<1 week	471	0.18 (0.08 to 0.28)	1.00	1.00
1 week to 1 month	187	0.05 (−0.09 to 0.19)	1.16 (0.62 to 2.18)	1.25 (0.65 to 2.39)
2-3 months	171	0.04 (−0.12 to 0.20)	0.70 (0.33 to 1.49)	0.69 (0.32 to 1.52)
4-6 months	133	0.24 (0.06 to 0.42)	1.27 (0.63 to 2.55)	1.31 (0.62 to 2.74)
7-9 months	61	0.16 (−0.12 to 0.42)	1.68 (0.70 to 4.05)	2.02 (0.80 to 5.10)
>9 months	67	0.20 (−0.04 to 0.44)	0.73 (0.24 to 2.19)	0.73 (0.23 to 2.27)

^*Standard deviation score for body mass index >1.64.

^†Adjusted for sex, parent's BMI, maternal smoking during pregnancy, birth weight, and social class.