Table 2. Odds ratios (ORs) for TNM classes in postmenopausal breast cancer by age at first and last childbirth, stratified by time interval between first and last childbirth.

Age at breast cancer diagnosis	T1	Tis* vr. T1			T2–T4** vr. T1			N0	N1–N3 vr. N0			M0	M1 vr. M0
	N	N	OR (95%CI)	P	N	OR (95%CI)	P	N	N	OR (95%CI)	P	N	N	OR (95%CI)	P
Time interval between first and last childbirth 1-4 yearsAge at first childbirth (year)
20-29 (Ref.)	2,574	55	1.00		1,503	1.00		2,607	1,145	1.00		2,863	75	1.00
≤19	277	5	0.84 (0.33–2.13)	0.71	138	0.08 (0.71–1.10)	0.25	20	132	1.14 (0.92–1.42)	0.24	23	5	0.63 (0.25–1.58)	0.33
30–39	569	13	1.00 (0.54–1.87)	1.00	415	1.14 (0.99-1.32)	0.09	1,574	252	0.90 (0.77–1.06)	0.21	1,679	31	1.61 (1.04–2.50)	0.03
≥40	9	0			12	2.22 (0.91–5.40)	0.08	58	7	1.79 (0.70–4.58)	0.23	75	1	2.96 (0.37–23.62)	0.31
Total	3,429	73			2,068			1,574	1,536			4,640	112

Bold type: 95% CI does not include 1.00.

Women with two or more children were included. ORs were adjusted for parity, region and occupation.

^*Carcinoma in situ.