Table 3. Association between prediagnostic reproductive factors and survival among serous EOC cases.

	Totala	Fatal casesb	Model 1		Model 2
	n	n (%)	HRc	95% CI	HRd	95% CI
Age at menarchee, years
<12	84	48 (57.1)	Ref.		Ref.
12	102	50 (49.0)	0.98	0.64–1.51	1.10	0.71–1.69
13	145	76 (52.4)	0.92	0.62–1.38	0.82	0.55–1.23
14	134	67 (50.0)	0.86	0.58–1.30	0.79	0.52–1.20
>14	98	54 (55.1)	1.02	0.66–1.57	0.92	0.59–1.44
Ptrend				0.80		0.69
Parouse
No	86	49 (57.0)	Ref.		Ref.
Yes	474	245 (51.7)	0.94	0.68–1.30	0.96	0.69–1.33
Number of FTPse,f
1	101	48 (47.5)	Ref.		Ref.
2	215	109 (50.7)	1.22	0.85–1.76	0.95	0.64–1.39
3+	148	82 (55.4)	1.47	1.00–2.16	1.10	0.73–1.65
Ptrend				0.05		0.38
Age at first FTPe,f, years
⩽20	61	31 (50.8)	Ref.		Ref.
>20–⩽25	208	94 (45.2)	0.68	0.44–1.04	0.59	0.38–0.92
>25–⩽30	145	83 (57.2)	0.82	0.53–1.28	0.75	0.47–1.20
>30	56	35 (62.5)	0.76	0.45–1.28	0.71	0.40–1.23
Ptrend				0.65		0.75
Breastfeedingf,g
Never	69	34 (49.3)	Ref.		Ref.
Ever	376	192 (51.1)	0.88	0.59–1.31	0.92	0.61–1.38
Duration of breastfeedingh, years
⩽3	130	65 (50.0)	Ref.		Ref.
>3–⩽6	75	39 (52.0)	1.05	0.68–1.61	1.07	0.68–1.69
>6–⩽12	75	33 (44.0)	0.61	0.38–0.98	0.60	0.37–0.99
>12–⩽24	69	38 (55.1)	0.93	0.59–1.45	0.90	0.56–1.43
>24	27	17 (63.0)	1.12	0.62–2.02	1.13	0.61–2.08
Ptrend				0.59		0.48
OC usee
Never	275	148 (53.8)	Ref.		Ref.
Ever	289	147 (50.9)	1.01	0.78–1.31	0.95	0.73–1.23
Duration of OC usei,j, years
⩽1	67	30 (44.8)	Ref.		Ref.
>1–⩽5	94	50 (53.2)	0.96	0.58–1.60	1.05	0.61–1.78
>5–⩽10	58	26 (44.8)	0.92	0.52–1.64	1.15	0.63–2.12
>10	46	28 (60.9)	1.42	0.80–2.51	1.31	0.71–2.40
Ptrend				0.31		0.42
Age at menopausek,l
⩽45	52	33 (63.5)	1.26	0.79–2.02	1.38	0.83–2.30
>45–⩽50	112	65 (58.0)	Ref.		Ref.
>50–⩽52	55	29 (52.7)	0.98	0.61–1.58	0.97	0.58–1.61
>52	68	45 (66.2)	1.16	0.77–1.77	1.11	0.71–1.75
Ptrend				0.88		0.64
MHT usee,k,m
Never	151	94 (62.3)	Ref.		Ref.
Ever	144	80 (55.6)	0.71	0.50–1.00	0.63	0.44–0.90
MHT timing of use at baselinee,k,m
Former	42	25 (59.5)	0.86	0.54–1.38	0.73	0.45–1.18
Current	101	54 (53.5)	0.65	0.44–0.96	0.60	0.39–0.90
MHT duration of use at baselinek,m,n, years
<5	78	43 (55.1)	0.81	0.54–1.22	0.79	0.51–1.21
⩾5	52	29 (55.8)	0.64	0.41–1.00	0.55	0.35–0.87
Ptrend				0.07		0.01
MHT formulation at baseline (current users only)k,m,o
E only	21	16 (76.2)	0.74	0.41–1.32	0.64	0.34–1.18
E+P	65	32 (49.2)	0.63	0.39–1.01	0.61	0.36–1.02
Other	7	3 (42.9)	0.35	0.08–1.53	0.35	0.08–1.50
Hysterectomyp
No	452	231 (51.1)	Ref.		Ref.
Yes	58	31 (53.4)	0.82	0.55–1.23	0.80	0.53–1.21
Total ovulatory yearsq
⩽27.5	119	57 (47.9)	Ref.		Ref.
>27.5–⩽33.0	117	65 (55.6)	1.34	0.90–1.98	1.33	0.87–2.04
>33.0–⩽36.5	124	55 (47.4)	0.75	0.49–1.13	0.73	0.47–1.13
>36.5	101	61 (60.4)	1.22	0.80–1.84	1.22	0.79–1.88
Ptrend				0.74		0.72

Abbreviations: CI=confidence interval; EOC=epithelial ovarian cancer; FTP=full term pregnancy; HR=hazard ratio, MHT=menopausal hormone therapy; OC=oral contraceptive.

^aTotal number of serous cases n=568.

^bTotal number of fatal serous cases n=298.

^cAdjusted for age at diagnosis (continuous) and stratified by study centre.

^dAdjusted for age at diagnosis (continuous), year of diagnosis (continuous), BMI (<23 kg m⁻², ⩾23–<25 (reference), ⩾25 –<30, ⩾30), tumour stage (local (reference), regional, metastatic and unknown), smoking status (never (reference), former, current and unknown) and stratified by study centre.

^eMissing for ⩽2.1% of the cohort.

^fAmong parous women only.

^gBreastfeeding was missing for 6.1% of the cohort.

^hAmong parous women who had ever breastfed.

ⁱAmong OC users only.

^jDuration of OC use was missing for 8.3% of women.

^kAmong postmenopausal women only.

^lAge at menopause was missing for 18.5% of postmenopausal women.

^mParticipants from Greece and Sweden were excluded from this analysis as detailed data on MHT use were unavailable.

ⁿMHT duration was missing for 9.7% of individuals who ever used MHT.

^oMHT formulation was missing for 7.9% of individuals who reported current use.

^pHysterectomy was missing for 10.2% of the cohort.

^qTotal ovulatory years was missing for 18.8% of the cohort.