Background
Methods
Study design and participants
Data collection and variable specification
Statistical analysis
Results
Univariate analysis
EP | IUP | OR [95 % CI] | p value | |||
---|---|---|---|---|---|---|
n
a
| (%) |
n
a
| (%) | |||
Age (year) | ||||||
≤20 | 24 | (1.00) | 32 | (1.33) | Reference | 0.16 |
20–24 | 363 | (15.06) | 398 | (16.47) | 1.22 [0.70, 2.10] | |
25–29 | 753 | (31.23) | 772 | (31.95) | 1.30 [0.76, 2.23] | |
30–34 | 793 | (32.89) | 755 | (31.25) | 1.40 [0.82, 2.40] | |
35–39 | 332 | (13.77) | 322 | (13.33) | 1.38 [0.79, 2.39] | |
≥40 | 146 | (6.06) | 137 | (5.67) | 1.42 [0.80, 2.53] | |
Marital status | ||||||
Married | 2067 | (85.80) | 2088 | (86.42) | Reference | 0.56 |
Unmarried | 342 | (14.20) | 328 | (13.58) | 0.92 [0.78, 1.08] | |
Birth place | ||||||
Shanghai | 698 | (28.95) | 775 | (32.08) | Reference | <10−3 |
Outside of Shanghai | 1713 | (71.05) | 1641 | (67.92) | 1.16 [1.03, 1.31] | |
Education attainment | ||||||
Collage or above | 1061 | (44.01) | 1378 | (57.04) | Reference | <10−3 |
High school | 314 | (13.02) | 280 | (11.59) | 1.46 [1.22, 1.74] | |
Middle school | 178 | (7.38) | 195 | (8.07) | 1.19 [0.95, 1.48] | |
Primary school or lower | 858 | (35.59) | 563 | (23.30) | 1.98 [1.73, 2.26] | |
Occupation | ||||||
Employed | 1682 | (69.88) | 1897 | (78.58) | Reference | <10−3 |
Self-employed | 262 | (10.89) | 184 | (7.62) | 1.61 [1.32, 1.96] | |
Unemployed | 463 | (19.24) | 333 | (13.80) | 1.57 [1.34, 1.83] | |
Personal annual income (RMB) | ||||||
<50,000 | 1165 | (48.32) | 1093 | (45.24) | Reference | 0.13 |
50,000-100,000 | 777 | (32.23) | 841 | (34.81) | 0.87 [0.76, 0.99] | |
> 100,000 | 469 | (19.45) | 482 | (19.95) | 0.91 [0.79, 1.06] | |
Smokingb | ||||||
None smoker | 2298 | (95.31) | 2294 | (96.18) | Reference | 0.41 |
Occasional smoker | 63 | (2.61) | 57 | (2.39) | 1.10 [0.77, 1.59] | |
Regular smoker | 50 | (2.07) | 34 | (1.43) | 1.47 [0.95, 2.28] | |
Institutionsc | ||||||
1 | 1404 | (58.23) | 1409 | (58.32) | Reference | 1.00 |
2 | 276 | (11.45) | 274 | (11.34) | 1.01 [0.84, 1.21] | |
3 | 291 | (12.07) | 293 | (12.13) | 1.00 [0.83, 1.19] | |
4 | 272 | (11.28) | 272 | (11.26) | 1.00 [0.84, 1.21] | |
5 | 168 | (6.97) | 168 | (6.95) | 1.00 [0.80, 1.26] |
EP | IUP | OR [95 % CI] | p value | |||
---|---|---|---|---|---|---|
n
a
| (%) |
n
a
| (%) | |||
Reproductive history | ||||||
Number of previous abortions | ||||||
0 | 873 | (36.88) | 930 | (38.49) | Reference | 0.71 |
1 | 763 | (32.23) | 756 | (31.29) | 1.08 [0.94, 1.23] | |
2 | 485 | (20.49) | 497 | (20.57) | 1.04 [0.89, 1.21] | |
≥ 3 | 246 | (10.39) | 233 | (9.64) | 1.13 [0.92, 1.38] | |
Parity | ||||||
0 | 1143 | (48.29) | 1280 | (52.98) | Reference | <10−3 |
1 | 994 | (41.99) | 973 | (40.27) | 1.14 [1.02, 1.30] | |
≥ 2 | 230 | (9.72) | 163 | (6.75) | 1.58 [1.27, 1.96] | |
Gynecologic history | ||||||
Previous EP | ||||||
No | 2093 | (86.81) | 2363 | (97.81) | Reference | <10−3 |
Yes | 318 | (13.19) | 53 | (2.19) | 6.77 [5.04, 9.11] | |
Serum Chlamydia trachomatis IgG test | ||||||
Negative | 1648 | (69.13) | 2099 | (89.55) | Reference | <10−3 |
Positive | 736 | (30.87) | 245 | (10.45) | 3.83 [3.27, 4.48] | |
Previous infertility | ||||||
No | 2005 | (83.26) | 2286 | (95.65) | Reference | <10−3 |
Yes | 403 | (16.74) | 104 | (4.35) | 4.42 [3.53, 5.53] | |
Categories of infertility | ||||||
No | 2005 | (83.26) | 2286 | (95.65) | Reference | <10−3 |
Tubal infertility | 326 | (13.54) | 73 | (3.05) | 5.09 [3.92, 6.61] | |
Non-tubal infertility | 77 | (3.20) | 31 | (1.30) | 2.83 [1.86, 4.32] | |
ARTs applied in the current cycle of conceptionb | ||||||
Spontaneous pregnancy | 278 | (68.98) | 72 | (69.23) | Reference | <10−3 |
IVF-ET | 58 | (14.39) | 3 | (2.88) | 5.01 [1.53, 16.44] | |
Other ARTsc | 46 | (11.41) | 18 | (17.31) | 0.66 [0.36, 1.21] | |
Chinese herb | 21 | (5.21) | 11 | (10.58) | 0.49 [0.23, 1.07] | |
Surgical history | ||||||
Previous cesarean sectiond | ||||||
No | 691 | (56.09) | 624 | (54.74) | Reference | 0.79 |
Yes | 541 | (43.91) | 516 | (45.26) | 0.95 [0.81, 1.11] | |
Previous adnexal surgery | ||||||
No | 1985 | (82.33) | 2322 | (96.19) | Reference | <10−3 |
Yes | 426 | (17.67) | 92 | (3.81) | 5.42 [4.29, 6.84] | |
Specific adnexal surgerye | ||||||
Ovarian surgery | 64 | (15.02) | 36 | (39.13) | 2.08 [1.38, 3.14] | <10−3 |
Surgery for EP | 237 | (55.62) | 38 | (41.30) | 7.30 [5.15, 10.33] | |
Tubal reconstructive surgery | 90 | (21.13) | 14 | (15.22) | 7.52 [4.27, 13.25] | |
Female sterilization | 21 | (4.93) | 2 | (2.17) | 12.28 [2.88, 52.45] | |
Reversal of tubal sterilization | 14 | (3.29) | 2 | (2.17) | 8.19 [1.86, 36.07] | |
Previous appendectomy | ||||||
No | 2303 | (95.84) | 2346 | (97.47) | Reference | 0.01 |
Yes | 100 | (4.16) | 61 | (2.53) | 1.67 [1.21, 2.31] |
EP | IUP | OR [95 % CI] | p value | |||
---|---|---|---|---|---|---|
n
a
| (%) |
n
a
| (%) | |||
Previous use of contraceptives | ||||||
LNG-EC | ||||||
No | 1283 | (53.57) | 1311 | (54.74) | Reference | 0.53 |
Yes | 1112 | (46.43) | 1084 | (45.26) | 1.05 [0.94, 1.17] | |
IUDs | ||||||
No | 1993 | (83.74) | 2106 | (88.27) | Reference | <10−3 |
Yes | 387 | (16.26) | 280 | (11.74) | 1.48 [1.25, 1.74] | |
OCPs | ||||||
No | 2254 | (94.47) | 2295 | (95.55) | Reference | 0.06 |
Yes | 132 | (5.53) | 107 | (4.45) | 1.25 [0.97, 1.63] | |
Other contraceptive methodsb | ||||||
No | 829 | (35.32) | 421 | (17.50) | Reference | <10−3 |
Yes | 1518 | (64.68) | 1985 | (82.50) | 0.39 [0.34, 0.45] | |
Current contraceptive methods | ||||||
No | 1337 | (55.87) | 1585 | (65.60) | Reference | <10−3 |
Other contraceptive methodsb | 447 | (18.68) | 653 | (27.03) | 0.81 [0.71, 0.93] | |
OCPs | 16 | (0.67) | 7 | (0.29) | 2.71 [1.11, 6.61] | |
LNG-EC | 341 | (14.25) | 145 | (6.00) | 2.79 [2.27, 3.43] | |
IUDs | 231 | (9.65) | 24 | (0.99) | 11.41 [7.45, 17.48] | |
Female sterilizationc | 21 | (0.88) | 2 | (0.08) | 12.45 [2.91, 53.18] |
Multivariate analysis
AOR [95 % CI] | p value | |
---|---|---|
Education attainment | ||
Collage or above | Reference | <10−3 |
High school | 1.21 [0.97, 1.50] | |
Middle school | 0.96 [0.74, 1.24] | |
Primary school or lower | 1.47 [1.23, 1.75] | |
Occupation | ||
Employed | Reference | <10−2 |
Self-employed | 1.30 [1.02, 1.66] | |
Unemployed | 1.33 [1.10, 1.62] | |
Previous ectopic pregnancy | ||
No | Reference | <10−3 |
Yes | 2.72 [1.83, 4.05] | |
Serum Chlamydia trachomatis IgG test | ||
Negative | Reference | <10−3 |
Positive | 3.18 [2.64, 3.84] | |
Previous infertility | ||
No | Reference | <10−3 |
Yes | 2.18 [1.66, 2.88] | |
ART applied in the current cycle of conception | ||
Spontaneous pregnancy | Reference | <10−3 |
IVF-ET | 9.28 [2.14, 40.38] | |
Other ARTsa | 0.80 [0.34, 1.88] | |
Chinese herb | 0.80 [0.41, 1.56] | |
Previous adnexal surgery | ||
No | Reference | <10−3 |
Yes | 2.09 [1.49, 2.93] | |
Previous appendectomy | ||
No | Reference | 0.01 |
Yes | 1.64 [1.13, 2.37] | |
Previous use of IUDs | ||
No | Reference | <10−3 |
Yes | 1.72 [1.39, 2.13] | |
Previous use of other contraceptive methodsb | ||
No | Reference | <10−3 |
Yes | 0.56 [0.47, 0.66] | |
Current contraceptive methods | ||
No | Reference | <10−3 |
Other contraceptive methodsb | 1.22 [0.99, 1.44] | |
OCPs | 3.02 [1.16, 7.86] | |
LNG-EC | 4.75 [3.79, 5.96] | |
IUDs | 16.43 [10.42, 25.89] | |
Female sterilization | 4.73 [1.04, 21.52] |
Tubal infertilitya | Non-tubal infertilityb | |||||||||
---|---|---|---|---|---|---|---|---|---|---|
EP | IUP | AOR [95 % CI]d | EP | IUP | AOR [95 % CI]d | |||||
n
c
| (%) |
n
c
| (%) |
n
c
| (%) |
n
c
| (%) | |||
ARTs applied in the current cycle of conception | ||||||||||
Spontaneous pregnancy | 223 | (68.41) | 50 | (68.49) | Reference | 55 | (71.43) | 22 | (70.97) | Reference |
IVF-ET | 55 | (16.87) | 2 | (2.74) | 8.99 [1.98, 40.84] | 3 | (3.90) | 1 | (3.23) | 2.52 [0.14, 44.67] |
Other ARTse | 29 | (8.9) | 12 | (16.44) | 0.59 [0.25, 1.39] | 17 | (22.08) | 6 | (19.36) | 0.94 [0.22, 3.98] |
Chinese herb | 19 | (5.83) | 9 | (12.33) | 0.78 [0.31, 2.01] | 2 | (2.60) | 2 | (6.45) | 0.35 [0.03, 4.50] |