Table 2.

Odds ratios with 95% confidence interval (OR, 95% CI) of breast cancer associated with quintiles of IGF-1 concentrations among women from the Finnish Maternity Cohort, 1983–2006.

	Quintiles
	q1	q2	q3	q4	q5	pTrend	pHeterogeneity
All women	ref.	1.20 (0.91–1.59)	1.05 (0.78–1.42)	0.92 (0.68–1.23)	1.08 (0.80–1.47)	0.68
	140/294	170/295	142/283	123/283	144/279
Women with information on gestational age1	ref.	1.04 (0.75–1.44)	0.88 (0.62–1.23)	0.73 (0.51–1.05)	1.01 (0.71–1.42)	0.46
	116/214	118/207	107/221	79/197	115/205
Ductal carcinoma	ref.	1.31 (0.96–1.78)	1.18 (0.84–1.64)	0.96 (0.68–1.35)	1.10 (0.78–1.56)	0.70
	106/235	142/240	119/225	96/223	111/223
Lobular carcinoma	ref.	0.89 (0.43–1.82)	0.63 (0.28–1.40)	0.70 (0.33–1.49)	0.88 (0.39–2.01)	0.59
	24/39	22/41	15/39	17/40	20/35
Age at pregnancy
< 29.2 years	ref.	0.99 (0.65–1.51)	1.03 (0.67–1.57)	0.77 (0.50–1.19)	0.83 (0.54–1.27)	0.19	0.07
	63/116	71/132	75/133	63/148	84/182
≥ 29.2 years	ref.	1.40 (0.97–2.02)	1.06 (0.70–1.60)	1.05 (0.69–1.59)	1.46 (0.94–2.28)	0.46
	77/178	99/163	67/150	60/135	60/97
Age at diagnosis
< 40.9 years	ref.	1.01 (0.65–1.56)	1.03 (0.66–1.62)	0.81 (0.52–1.27)	0.84 (0.53–1.31)	0.21	0.09
	56/104	72/133	80/142	66/151	84/183
≥ 40.9 years	ref.	1.36 (0.95–1.94)	1.01 (0.67–1.51)	0.99 (0.65–1.49)	1.44 (0.93–2.22)	0.50
	84/190	98/162	62/141	57/132	60/96
Lag-time
< 11.3 years	ref.	1.24 (0.81–1.91)	1.15 (0.73–1.81)	0.83 (0.53–1.31)	1.10 (0.69–1.74)	0.51	0.96
	55/116	89/152	77/141	59/153	77/149
≥ 11.3 years	ref.	1.17 (0.81–1.69)	0.96 (0.65–1.43)	1.03 (0.69–1.54)	1.08 (0.71–1.64)	0.96
	85/178	81/143	65/142	64/130	67/130

¹Adjustment for gestational age resulted in identical risk estimates with the exception of a minor change in the top quintile risk (1.00 (0.71–1.41), p = 0.44)