Table 6. IRs of unexpected vaginal bleeding and HRs with 95% CIs by vaccination status, hormone status, and years since last menstrual bleeding in postmenopausal women.

HRT, hormone replacement therapy; hormonal IUD, hormonal intrauterine device; cHR, crude HR; aHR, HR adjusted for age.

	Unexpected vaginal bleeding	PY	IR per 100 PY (95% CI)	cHR (95% CI)	aHR (95% CI)
Postmenopausal women
Not using hormones (n = 5681)
Non/prevaccination	52	2001	2.6 (2.0–3.4)	Ref	Ref
First or second dose (≤28 days)	56	788	7.1 (5.5–9.2)	2.0 (1.2–3.4)	2.9 (1.7–4.9)
HRT (n = 934)
Non/prevaccination	36	332	10.9 (7.8–15.0)	Ref	Ref
First or second dose (≤28 days)	40	123	32.4 (23.8–44.2)	2.3 (1.2–4.3)	2.8 (1.5–5.2)
Hormonal IUD (n = 692)
Non/prevaccination	21	268	7.8 (5.1–12.0)	Ref	Ref
First or second dose (≤28 days)	24	90	26.7 (17.9–39.8)	2.2 (1.0–5.2)	2.4 (1.0–5.5)
Perimenopausal women
Not using hormones (n = 3059)
Non/prevaccination	136	1233	11.0 (9.3–13.0)	Ref	Ref
First or second dose (≤28 days)	223	368	60.7 (55.2–69.2)	4.9 (3.6–6.7)	4.9 (3.6–6.6)
HRT (n = 538)
Non/prevaccination	54	197	27.5 (21.0–35.9)	Ref	Ref
First or second dose (≤28 days)	55	63	87.7 (67.3–114.3)	2.9 (1.7–5.0)	2.9 (1.7–5.0)
Hormonal IUD (n = 3274)
Non/prevaccination	180	1277	14.1 (12.2–16.3)	Ref	Ref
First or second dose (≤28 days)	231	397	58.1 (51.1–66.1)	3.8 (2.9–5.1)	3.8 (2.9–5.1)
Premenopausal women
Not using hormones (n = 1022)
Non/prevaccination	38	426	8.9 (6.5–12.3)	Ref	Ref
First or second dose (≤28 days)	42	122	34.6 (25.5–46.8)	4.0 (2.1–7.4)	4.1 (2.2–7.7)
Hormonal IUD (n = 5199)
Non/prevaccination	247	2048	12.1 (10.6–13.7)	Ref	Ref
First or second dose (≤28 days)	428	612	69.9 (63.6–76.9)	4.8 (3.9–5.9)	4.8 (3.9–5.9)
Other hormonal contraception* (n = 595)
Non/prevaccination	27	246	11.0 (7.5–16.0)	Ref	Ref
First or second dose (≤ 28 days)	37	70	52.8 (38.3–72.8)	4.2 (2.1–8.5)	4.4 (2.2–8.7)

*Combination pill, progestin-only pill, or contraceptive implant.