Table 2. Weight change since age 18 and incidence of breast cancer among premenopausal participants of the Nurses' Health Study, 1980-2008, and Nurses' Health Study II, 1993-2007 ^*.

			Age-adjusted		Covariate-adjusted		Covariate-adjusted controlling for weight at age 18
Weight change since age 18 (kg)	No. of cases	Person- years	HR	95% CI	HR†	95% CI	HR‡	95% CI
Lost ≥ 5	49	44020	0.61	(0.44, 0.85)	0.59	(0.42, 0.82)	0.75	(0.52, 1.09)
Lost 2 - 4.9	63	44015	0.81	(0.60, 1.09)	0.80	(0.59, 1.07)	0.87	(0.65, 1.18)
Stable§	147	79707	1.00		1.00		1.00
Gained 2 - 4.9	232	128950	0.99	(0.80, 1.22)	0.99	(0.80, 1.22)	0.98	(0.79, 1.20)
Gained 5 - 9.9	447	236235	0.99	(0.82, 1.20)	0.99	(0.82, 1.20)	0.97	(0.80, 1.17)
Gained 10 - 14.9	342	172777	0.99	(0.81, 1.20)	0.99	(0.82, 1.21)	0.97	(0.80, 1.19)
Gained 15 - 19.9	181	107300	0.85	(0.68, 1.06)	0.86	(0.68, 1.07)	0.85	(0.68, 1.06)
Gained 20 - 24.9	128	72236	0.87	(0.65, 1.17)	0.88	(0.66, 1.18)	0.89	(0.67, 1.20)
Gained ≥ 25	222	128935	0.75	(0.55, 1.02)	0.74	(0.52, 1.04)	0.78	(0.55, 1.11)
P for trend in weight gain*			0.002		0.01		0.08

^*Restricted to women who had stable weight or stable weight gain/loss since age 18 for at least two consecutive questionnaire cycles

^†Adjusted for age, family history of breast cancer, history of benign breast disease, height, age at menarche, age at first birth, parity, alcohol use, physical activity, current and past oral contraceptive use

^‡Additionally adjusted for weight at age 18 in kg (continuous)

^§Gain or loss up to 2 kg