Variable | Value | Cases / non-cases | Model 1 HRa (95 % CI) | Model 2 HRb (95 % CI) |
---|---|---|---|---|
Parous | No | 2,220 / 45,746 | 1.00 (reference) | 1.00 (reference) |
Yes | 11,757 / 254,871 | 0.80 (0.76–0.83) | 0.80 (0.76–0.84) | |
Number of FTPsc | 1 | 2,307 / 45,881 | 1.00 (reference) | 1.00 (reference) |
2 | 5,026 / 122,430 | 0.87 (0.83–0.91) | 0.91 (0.86–0.96) | |
3 | 2,529 / 56,316 | 0.83 (0.79–0.88) | 0.87 (0.82–0.92) | |
4 | 1,047 / 16,278 | 0.97 (0.90–1.04) | 0.98 (0.91–1.06) | |
5 | 350 / 4,448 | 0.97 (0.87–1.09) | 0.97 (0.86–1.09) | |
≥6 | 237 / 2,290 | 1.09 (0.95–1.25) | 1.08 (0.94–1.24) | |
P for trendd | 0.91 | 0.79 | ||
Age at first FTP, yearsc | ≤20 | 1,812 / 37,390 | 1.30 (1.23–1.38) | 1.10 (1.04–1.17) |
21–23 | 3,121 / 68,203 | 1.13 (1.07–1.19) | 1.05 (1.00–1.11) | |
24–25 | 2,173 / 49,889 | 1.02 (0.97–1.08) | 1.00 (0.95–1.06) | |
26–30 | 3,287 / 72,649 | 1.00 (reference) | 1.00 (reference) | |
≥31 | 1,281 / 25,749 | 1.08 (1.01–1.15) | 1.08 (1.01–1.16) | |
Breastfeedingc | Never | 1,721 / 36,691 | 1.00 (reference) | 1.00 (reference) |
Ever | 9,148 / 202,910 | 0.88 (0.83–0.93) | 0.92 (0.87–0.97) | |
Breastfeeding, monthse | ≤1 | 949 / 20,021 | 1.00 (reference) | 1.00 (reference) |
>1 to ≤3 | 1,753 / 39,935 | 1.01 (0.93–1.09) | 1.01 (0.93–1.09) | |
>3 to ≤6 | 1,846 / 41,685 | 0.94 (0.87–1.02) | 0.97 (0.89–1.05) | |
>6 to ≤12 | 2,224 / 47,802 | 0.90 (0.83–0.98) | 0.95 (0.88–1.03) | |
>12 to ≤18 | 986 / 23,319 | 0.81 (0.74–0.89) | 0.88 (0.80–0.97) | |
>18 | 1,276 / 27,949 | 0.88 (0.80–0.96) | 0.97 (0.89–1.07) | |
P for trendd | 0.013 | 0.85 | ||
Infertilityf | No | 8,958 / 199,770 | 1.00 (reference) | 1.00 (reference) |
Yes | 360 / 9,869 | 1.06 (0.95–1.18) | 1.06 (0.95–1.18) | |
OC use in never or former | Never | 6,379 / 100,292 | 1.00 (reference) | 1.00 (reference) |
smokers at baselineg | Ever | 3,736 / 140,642 | 0.90 (0.85–0.94) | 0.90 (0.86–0.95) |
Formerh | 3,475 / 122,414 | 0.89 (0.85–0.94) | 0.90 (0.86–0.95) | |
Currenth | 140 / 12,959 | 0.89 (0.74–1.07) | 0.92 (0.76–1.11) | |
Duration OC use, yearsg,i | ≤1 | 679 / 25,490 | 1.00 (reference) | 1.00 (reference) |
>1 to <5 | 721 / 30,600 | 0.99 (0.89–1.10) | 0.99 (0.89–1.11) | |
5 to <10 | 705 / 30,859 | 0.95 (0.85–1.06) | 0.96 (0.86–1.07) | |
10 to <15 | 616 / 21,267 | 1.05 (0.94–1.18) | 1.06 (0.94–1.18) | |
≥15 | 526 / 18,583 | 1.02 (0.90–1.15) | 1.02 (0.91–1.16) | |
P for trendd | 0.36 | 0.32 | ||
Age at menarche, years | <12 | 1,977 / 45,763 | 1.00 (reference) | 1.00 (reference) |
12 | 2,714 / 65,654 | 0.92 (0.86–0.97) | 0.95 (0.89–1.01) | |
13 | 3,378 / 79,701 | 0.88 (0.84–0.94) | 0.92 (0.87–0.98) | |
14 | 3,224 / 66,159 | 0.89 (0.84–0.95) | 0.93 (0.88–0.98) | |
≥15 | 2,774 / 47,743 | 0.88 (0.82–0.93) | 0.90 (0.85–0.96) | |
P for trendd | 0.004 | 0.038 | ||
Age at natural menopause, yearsj | ≤45 | 1,080 / 12,399 | 1.15 (1.07–1.24) | 1.09 (1.01–1.17) |
46–50 | 2,427 / 32,488 | 1.00 (reference) | 1.00 (reference) | |
51–52 | 1,064 / 14,537 | 0.88 (0.82–0.95) | 0.91 (0.85–0.99) | |
53–55 | 1,003 / 12,753 | 0.86 (0.80–0.93) | 0.92 (0.85–0.99) | |
>55 | 339 / 3,287 | 0.90 (0.80–1.01) | 0.95 (0.85–1.07) | |
P for trendd | <0.001 | <0.001 | ||
Total ovulatory lifespan, yearsk,l | 0–22 | 1,180 / 56,387 | 1.00 (reference) | 1.00 (reference) |
22–29 | 1,621 / 53,629 | 0.96 (0.89–1.05) | 0.99 (0.91–1.07) | |
29–34 | 2,148 / 52,270 | 0.92 (0.84–0.99) | 0.96 (0.89–1.04) | |
≥34 | 3,115 / 51,923 | 0.89 (0.82–0.97) | 0.98 (0.91–1.06) | |
P for trendd | 0.004 | 0.86 | ||
Oophorectomyl | No | 11,167 / 266,535 | 1.00 (reference) | 1.00 (reference) |
Yes | 1,202 / 18,603 | 1.05 (0.98–1.11) | 1.01 (0.93–1.10) | |
Hysterectomyl | No | 10,606 / 257,298 | 1.00 (reference) | 1.00 (reference) |
Yes | 1,972 / 30,608 | 1.01 (0.96–1.06) | 1.00 (0.94–1.05) |