Table 1 Characteristics of the study population at the start of follow-up (Questionnaire 2) according to healthy lifestyle index score change in the Norwegian Women and Cancer Study (N = 66,233)

Age(years)

58.2 (6.3)

57.2 (5.9)

57.3 (6.0)

57.2 (5.9)

57.3 (6.0)

57.3 (6.1)

57.4 (6.2)

57.3 (6.0)

0(0)

Education (years)

12.3 (3.5)

12.5 (3.4)

12.7 (3.4)

12.6 (3.4)

12.7 (3.5)

12.6 (3.4)

12.6 (3.4)

12.5 (3.4)

3471 (5%)

HLI score at Q2, median (IQR)

136 (11, 15)

10 (9, 12)

12 (10, 14)

13 (10, 14)

13 (11, 15)

14 (12, 15)

14 (12, 16)

14 (13, 16)

16,343 (25%)

Physical activity score change

0.1 (1.4)

-1.2 (1.3)

-0.5 (1.1)

-0.2 (1.1)

0.1 (1.0)

0.5 (1.1)

0.8 (1.1)

1.5 (1.3)

11,969 (18%)

BMI score change

-0.3 (0.8)

-0.7 (0.8)

-0.5 (0.7)

-0.4 (0.7)

-0.2 (0.7)

-0.1 (0.7)

-0.0 (0.7)

0.2 (0.8)

3713 (6%)

Smoking score change

0.1 (0.5)

-0.0 (0.6)

0.0 (0.5)

0.1 (0.5)

0.1 (0.5)

0.1 (0.5)

0.2 (0.5)

0.3 (0.6)

5939 (9%)

Alcohol score change

-0.1 (0.7)

-0.4 (0.7)

-0.2 (0.7)

-0.2 (0.6)

-0.1 (0.6)

-0.0 (0.6)

0.0 (0.6)

0.2 (0.7)

2920 (4%)

Diet score change

0.0 (1.6)

-1.5 (1.4)

-0.8 (1.2)

-0.4 (1.2)

0.1 (1.1)

0.6 (1.2)

1.0 (1.2)

1.6 (1.3)

6914 (10%)

Height (cm)

166.0 (5.7)

166.2 (5.7)

166.4 (5.7)

166.1 (5.6)

166.3 (5.7)

166.2 (5.6)

166.3 (5.7)

166.4 (5.6)

1705 (3%)

Physical activity level (> = 6)^a, N (%)

30,391 (46%)

2182 (30%)

2457 (44%)

2457 (44%)

4262 (56%)

4064 (60%)

3041 (65%)

3956 (73%)

8572 (13%)

Body mass index (kg/m²)

25.4 (4.2)

26.3 (4.1)

25.7 (4.1)

25.5 (4.1)

25.1 (4.1)

25.1 (4.2)

24.9 (4.1)

25.0 (4.1)

2633 (4%)

Smoking status, N (%)

2913 (4%)

 Never

22,653 (34%)

2475 (35%)

2189 (39%)

2726 (38%)

3007 (39%)

2550 (38%)

1724 (37%)

1650 (30%)

 Former

26,942 (41%)

2986 (42%)

2263 (40%)

2907 (41%)

3090 (40%)

2751 (41%)

2012 (43%)

2687 (49%)

 Current

13,725 (21%)

1708 (24%)

1184 (21%)

1466 (21%)

1541 (20%)

1442 (21%)

937 (20%)

1108 (20%)

Alcohol intake (g/day)

4.0 (5.0)

5.1 (5.8)

4.5 (5.2)

4.4 (5.3)

4.2 (4.9)

4.0 (4.9)

3.9 (4.5)

3.8 (4.6)

3387 (5%)

Diet score (0–18)

8.8 (2.5)

7.3 (2.3)

8.0 (2.4)

8.5 (2.5)

9.0 (2.5)

9.3 (2.3)

9.6 (2.2)

9.9 (2.1)

4786 (7%)

Postmenopausal, N (%)

52,110 (79%)

5415 (76%)

4270 (76%)

5346 (75%)

5798 (76%)

5048 (75%)

3528 (75%)

4111 (76%)

0(0)

Age at menarche (years)

13.3 (1.4)

13.2 (1.4)

13.3 (1.4)

13.3 (1.4)

13.3 (1.4)

13.3 (1.4)

13.3 (1.4)

13.3 (1.4)

921 (1%)

Hormone replacement therapy status, N (%)

0(0)

 Never

45,276 (68%)

4970 (69%)

3865 (69%)

4924 (69%)

5260 (69%)

4521 (67%)

3158 (68%)

3640 (67%)

 Former

6852 (10%)

705 (10%)

546 (10%)

650 (9%)

737 (10%)

705 (10%)

479 (10%)

550 (10%)

 Current

14,105 (21%)

1494 (21%)

1225 (22%)

1525 (21%)

1641 (21%)

1517 (22%)

1036 (22%)

1255 (23%)

Oral contraceptive ever use, N (%)

35,451 (54%)

4205 (59%)

3262 (58%)

3993 (56%)

4344 (57%)

3823 (57%)

2669 (57%)

3143 (58%)

0(0)

Parity, N (%)

0(0)

 0

5411 (8%)

576 (8%)

475 (8%)

580 (8%)

611 (8%)

585 (9%)

398 (9%)

465 (9%)

 1–2

34,666 (52%)

3825 (53%)

2987 (53%)

3850 (54%)

4149 (54%)

3667 (54%)

2524 (54%)

3056 (56%)

  > 2

26,156 (39%)

2768 (39%)

2174 (39%)

2669 (38%)

2878 (38%)

2491 (37%)

1751 (37%)

1924 (35%)

Cumulative breastfeeding duration (months), N (%)

0(0)

 0

34,402 (52%)

3950 (55%)

3229 (57%)

4063 (57%)

4351 (57%)

3827 (57%)

2696 (58%)

3023 (56%)

  <  = 12

16,797 (25%)

1622 (23%)

1251 (22%)

1585 (22%)

1716 (22%)

1599 (24%)

1116 (24%)

1350 (25%)

  > 12

15,034 (23%)

1597 (22%)

1156 (21%)

1451 (20%)

1571 (21%)

1317 (20%)

861 (18%)

1072 (20%)

Family history of breast cancer in the first degree, N (%)

5180 (8%)

559 (8%)

421 (7%)

570 (8%)

571 (7%)

506 (8%)

366 (8%)

385 (7%)

(0)