Table 3.

Association of BMI change and ER+ breast cancer risk stratified by parity.

	Controls		Cases								Pheterongeneity
	(n=927)		ER−/PR−/HER2− (n=181)				ER+a (n=772)
	n	%	n	%	ORc	95%CI	n	%	ORc	95%CI
Nulliparous (never had a live birth)
BMI change from age 18 to reference (kg/m2)
<5.0	112	59%	30	60%	1.0	Ref	154	74%	1.0	Ref
5.0-<10.0	48	25%	16	32%	1.3	0.6-2.6	38	18%	0.5b	0.3-0.9
≥10.0	29	15%	4	8%	0.5	0.2-1.5	15	7%	0.3b	0.2-0.6
Ptrend						0.4				<0.001	0.08
Continuous (kg/m2)					0.97	0.91-1.04			0.93	0.89-0.97
Parous (ever had a live birth)
BMI change from age 18 to reference (kg/m2)
<5.0	433	59%	64	49%	1.0	Ref	342	61%	1.0	Ref
5.0-<10.0	211	29%	36	27%	1.2	0.8-1.9	148	26%	0.9	0.7-1.2
≥10.0	94	13%	31	24%	2.1b	1.3-3.4	75	13%	1.0	0.7-1.4
Ptrend						0.008				0.7	0.0045
Continuous (kg/m2)					1.06	1.02-1.10			1.00	0.97-1.02
Pinteraction						0.11				0.002

^aRegardless of PR/HER2 status.

^bP < 0.05.

^cORs are adjusted by age at reference, reference year, race/etnicity.