. 2013 Sep 5;178(9):1403–1413. doi: 10.1093/aje/kwt154

Table 2.

Hazard Ratios and 95% Confidence Intervals for the Associations of Reproductive Factors and Exogenous Hormone Use With Pancreatic Cancer Risk Among 118,164 Participants in the California Teachers Study, 1995–2009

	No. of Cases	Person-years	Multivariable HR^a	95% CI
	All Participants
Total	323	1,505,060
Age at menarche, years
≤11	68	339,542	1.00	Referent
12	82	408,821	0.98	0.71, 1.35
13	84	437,735	0.92	0.66, 1.26
≥14	82	299,088	1.22	0.88, 1.69
P for trend			0.31
Duration of OC use, years
Never	156	437,932	1.00	Referent
<1	17	115,325	1.10	0.65, 1.85
1–4	43	342,562	1.15	0.78, 1.68
5–9	36	312,200	1.12	0.74, 1.69
≥10	47	213,768	1.72	1.19, 2.49
P for trend			0.014^b
Parity/No. of full-term pregnancies
Nulligravid	49	302,273	1.00	Referent
Gravid, nulliparous	16	90,651	1.44	0.82, 2.55
1	44	230,145	1.13	0.75, 1.70
2	101	492,786	1.10	0.78, 1.55
3	62	239,027	0.98	0.67, 1.43
≥4	41	124,123	0.94	0.62, 1.44
P for trend			0.68
Number of full-term pregnancies among parous women
1	44	230,145	1.00	Referent
2	101	492,786	0.98	0.69, 1.41
3	62	239,027	0.88	0.60, 1.30
≥4	41	124,123	0.83	0.55, 1.29
P for trend			0.31
Age at first full-term pregnancy among parous women, years
<22	34	155,583	1.00	Referent
22–24	66	236,863	1.13	0.75, 1.72
25–29	101	442,541	1.12	0.76, 1.67
≥30	47	251,080	1.09	0.69, 1.74
P for trend			0.76
Breastfeeding^c
Never breastfed	73	237,291	1.00	Referent
Ever	175	846,062	1.07	0.81, 1.41
Menopausal status/HT use at baseline^d
Premenopausal	29	631,941	1.00	Referent
Postmenopausal, never used HT	87	169,758	1.31	0.67, 2.59
Postmenopausal, ever used HT	176	574,109	0.93	0.48, 1.78
	Postmenopausal Participants Only
HT use at baseline^d
Never HT user	87	169,758	1.00	Referent
Ever HT user	176	574,109	0.70	0.54, 0.91
HT formulation at baseline^d
Never HT user	87	169,758	1.00	Referent
Ever HT user
Used ET only	74	215,100	0.64	0.47, 0.88
Used EPT only	68	260,774	0.81	0.58, 1.14
Used both ET and EPT	36	107,621	0.72	0.49, 1.06
Recency of use at baseline^d
Never HT user	87	169,758	1.00	Referent
Former HT user	43	105,054	0.70	0.48, 1.01
Current ET user	52	192,503	0.59	0.42, 0.84
Current EPT user	75	260,794	0.84	0.61, 1.17
Recency of use at baseline; follow-up truncated at June 30, 2002^d
Never HT user	31	86,296	1.00	Referent
Former HT user	13	53,956	0.58	0.30, 1.10
Current ET user	19	96,561	0.66	0.37, 1.17
Current EPT user	24	128,057	1.00	0.57, 1.77
Age at menopause, years
<47	52	161,767	1.00	Referent
47–49	52	113,213	1.29	0.88, 1.90
50–52	51	157,396	0.79	0.53, 1.17
≥53	65	141,484	0.98	0.68, 1.43

Abbreviations: CI, confidence interval; EPT, estrogen-plus-progestin therapy; ET, estrogen-only therapy; HR, hazard ratio; HT, hormone therapy; OC, oral contraceptive.

^a All models were stratified by age at baseline (in single years) and adjusted for race/ethnicity (non-Hispanic white, black, or other), body mass index, measured as weight in kilograms divided by height in meters squared (<25, 25 to <30, ≥30, or unknown), menopausal status (premenopausal, postmenopausal, or unknown), HT use (never, ET only, EPT only, both ET and EPT, progestin-only therapy, or unknown), age at menarche (<14 years, ≥14 years, or unknown), total number of full-term pregnancies (nulligravid, gravid nulliparous, 1–2 full-term pregnancies, ≥3 full-term pregnancies, or unknown), smoking status (never, former, current, or unknown), and history of diabetes (no or yes).

^b Includes participants who never used OCs.

^c Among participants who ever had a live birth (n = 84,807).

^d Excludes participants who used a progestin-only therapy (n = 1,116).