Table 2. Previous use of LNG-EC.
| EP | IUP | NonP | OR1 [95%CI] | OR2 [95%CI] | AOR1 [95%CI]b | AOR2 [95%CI]b | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| n a | (%) | n a | (%) | n a | (%) | EP vs. NonP | EP vs. IUP | EP vs. NonP | EP vs. IUP | |
| Previous use of LNG-EC | ||||||||||
| Not used | 1,283 | (53.57) | 1,311 | (54.74) | 1,330 | (55.12) | Reference | Reference | Reference | Reference |
| Yes | 1,112 | (46.43) | 1,084 | (45.26) | 1,083 | (44.88) | 0.94 [0.84, 1.05] | 0.95 [0.85, 1.07] | 0.99 [0.85, 1.18] | 0.95 [0.82, 1.10] |
| Total times of LNG-EC use | ||||||||||
| Not used | 1,283 | (53.57) | 1,311 | (54.74) | 1,330 | (55.12) | Reference | Reference | Reference | Reference |
| 1–2 | 585 | (24.43) | 568 | (23.72) | 566 | (23.46) | 1.07 [0.93, 1.23] | 1.05 [0.92, 1.21] | 1.08 [0.89, 1.31] | 1.17 [0.99, 1.38] |
| 3–4 | 290 | (12.11) | 305 | (12.73) | 334 | (13.84) | 0.90 [0.75, 1.07] | 0.97 [0.81, 1.16] | 0.89 [0.69, 1.13] | 0.93 [0.74, 1.17] |
| ≥5 | 237 | (9.89) | 211 | (8.81) | 183 | (7.58) | 1.34 [1.09, 1.65] | 1.15 [0.94, 1.40] | 0.94 [0.70, 1.26] | 0.85 [0.66, 1.11] |
| P for trend | 0.15 | 0.35 | 0.71 | 0.67 | ||||||
| Times of LNG-EC use in the past one year | ||||||||||
| Not used | 1,283 | (53.57) | 1,311 | (54.74) | 1,330 | (55.12) | Reference | Reference | Reference | Reference |
| 0 | 542 | (22.63) | 566 | (23.63) | 659 | (27.31) | 0.85 [0.74, 0.98] | 0.98 [0.85, 1.13] | 0.94 [0.78, 1.13] | 1.15 [0.97, 1.36] |
| 1–2 | 349 | (14.57) | 355 | (14.82) | 294 | (12.18) | 1.23 [1.04, 1.46] | 0.96 [0.82, 1.14] | 1.08 [0.84, 1.39] | 0.89 [0.71, 1.10] |
| 3–4 | 125 | (5.22) | 99 | (4.13) | 74 | (3.07) | 1.75 [1.30, 2.36] | 1.52 [1.14, 2.03] | 1.16 [0.78, 1.72] | 1.05 [0.74, 1.50] |
| ≥5 | 96 | (4.01) | 64 | (2.67) | 56 | (2.32) | 1.78 [1.27, 2.49] | 1.53 [1.11, 2.12] | 1.31 [0.83, 2.06] | 0.92 [0.61, 1.39] |
| P for trend | <10−4 | 0.01 | 0.47 | 0.75 | ||||||
| Last use-current cycle interval (months) | ||||||||||
| Not used | 1,283 | (53.57) | 1,311 | (54.74) | 1,330 | (55.12) | Reference | Reference | Reference | Reference |
| >12 | 542 | (22.63) | 566 | (23.63) | 659 | (27.31) | 0.85 [0.74, 0.98] | 0.98 [0.85, 1.13] | 0.94 [0.78, 1.13] | 1.15 [0.97, 1.36] |
| 7–12 | 231 | (9.65) | 246 | (10.27) | 199 | (8.24) | 1.20 [0.98, 1.48] | 0.96 [0.79, 1.17] | 1.13 [0.85, 1.50] | 0.88 [0.68, 1.13] |
| 4–6 | 189 | (7.89) | 173 | (7.22) | 150 | (6.22) | 1.31 [1.04, 1.64] | 1.12 [0.90, 1.39] | 1.04 [0.75, 1.44] | 0.85 [0.64, 1.13] |
| 1–3 | 150 | (6.26) | 99 | (4.13) | 75 | (3.11) | 2.07 [1.56, 2.76] | 1.55 [1.19, 2.02] | 1.26 [0.86, 1.85] | 1.13 [0.81, 1.57] |
| P for trend | <10−4 | 0.01 | 0.37 | 0.86 | ||||||
EP, ectopic pregnancy; IUP, intrauterine pregnancy; NonP, non-pregnancy; LNG-EC, levonorgestrel emergency contraception; OR, odds ratio; AOR, adjusted odds ratio; CI, confidence interval.
aThe sum does not necessarily equal the sample size for all variables because of missing data.
bInstitutions was used as a random effect in the mixed effects model to adjusted ORs for birth place, education attainment, occupation, parity, previous ectopic pregnancy, presence of serum Chlamydia trachomatis IgG, previous infertility, previous adnexal surgery, previous appendectomy, previous contraceptive methods (IUDs and other contraceptive methods), and current contraceptive methods (no, IUDs, OCPs, sterilization, LNG-EC, and other contraceptive methods).