Table 1.
Comparison of basic characteristics. Median (P25, P75).
| Characteristics | Before PSM | After PSM | ||||||
|---|---|---|---|---|---|---|---|---|
| Total (n = 11,491) | Group A (n = 2,731) | Group B (n = 9,120) | p | Total (n = 9,424) | Group A (n = 2,365) | Group B (n = 7,059) | p | |
| Female age (years) | 31.00 [28.00, 33.00] | 31.00 [28.00, 33.00] | 31.00 [28.00, 33.00] | 0.400 | 31.00 [28.00, 34.00] | 31.00 [28.00, 33.00] | 31.00 [28.00, 34.00] | 0.830 |
| Age <35 | 9,518 (82.8%) | 1,962 (82.7%) | 7,556 (82.9%) | 0.93 | 7,735 (82.1%) | 1,957 (82.7%) | 5,778 (81.9%) | 0.341 |
| Age ≥35 | 1,973 (17.2%) | 409 (17.3%) | 1,564 (17.1%) | 1,689 (17.9%) | 408 (17.3%) | 1,281 (18.1%) | ||
| BMI (kg/m2) | 21.83 [19.98, 24.14] | 22.04 [20.20, 24.41] | 21.76 [19.95, 24.04] | 0.010 | 22.03 [20.07, 24.25] | 22.04 [20.20, 24.36] | 22.03 [20.03, 24.23] | 0.829 |
| Underweight (<18.5) | 1,067 (9.3%) | 212 (8.9%) | 855 (9.4%) | <0.001 | 807 (8.6%) | 211 (8.9%) | 596 (8.4%) | 0.026 |
| Normal weight (18.5 ≤ 24.0) | 7,322 (63.7%) | 1,455 (61.4%) | 5,867 (64.3%) | 5,948 (63.1%) | 1,455 (61.5%) | 4,493 (63.6%) | ||
| Overweight (24.0 ≤ 28.0) | 2,430 (21.1%) | 579 (24.4%) | 1,851 (20.3%) | 2,128 (22.6%) | 579 (24.5%) | 1,549 (21.9%) | ||
| Obesity (≥28.0) | 672 (5.8%) | 125 (5.3%) | 547 (6.0%) | 541 (5.7%) | 120 (5.1%) | 421 (6.0%) | ||
| Gravidity (number of pregnancies) | 1.00 [0.00, 2.00] | 1.00 [0.00, 2.00] | 1.00 [0.00, 2.00] | 0.960 | 1.00 [0.00, 2.00] | 1.00 [0.00, 2.00] | 1.00 [0.00, 2.00] | 0.547 |
| Parity (number of births) | 0.00 [0.00, 0.00] | 0.00 [0.00, 0.00] | 0.00 [0.00, 0.00] | 0.040 | 0.00 [0.00, 0.00] | 0.00 [0.00, 0.00] | 0.00 [0.00, 0.00] | 0.113 |
| Infertile duration (years) | 3.00 [2.00, 5.00] | 3.00 [1.00, 5.00] | 3.00 [2.00, 5.00] | 0.790 | 3.00 [2.00, 5.00] | 3.00 [1.00, 5.00] | 3.00 [2.00, 5.00] | 0.716 |
| Infertility Duration ≥10 years (%) | 552 (4.8%) | 119 (5.0%) | 433 (4.7%) | 0.620 | 456 (4.8%) | 119 (5.0%) | 337 (4.8%) | 0.653 |
| Infertile type | 0.427 | |||||||
| Primary infertility | 5,616 (48.9%) | 1,176 (49.6%) | 4,440 (48.7%) | 0.440 | 4,550 (48.3%) | 1,173 (49.6%) | 3,377 (47.8%) | 0.145 |
| Secondary infertility | 5,875 (51.1%) | 1,195 (50.4%) | 4,680 (51.3%) | 4,874 (51.7%) | 1,192 (50.4%) | 3,682 (52.2%) | ||
| Infertile factors | ||||||||
| Tubal/pelvic factor | 2,129 (18.5%) | 432 (18.2%) | 1,697 (18.6%) | 0.690 | 1,762 (18.7%) | 432 (18.3%) | 1,330 (18.8%) | 0.555 |
| Polycystic ovary syndrome | 321 (2.8%) | 50 (2.1%) | 271 (3.0%) | 0.030 | 246 (2.6%) | 50 (2.1%) | 196 (2.8%) | 0.094 |
| Ovarian dysfunction | 150 (1.3%) | 30 (1.3%) | 120 (1.3%) | 0.930 | 131 (1.4%) | 30 (1.3%) | 101 (1.4%) | 0.630 |
| Insulin resistance | 11 (0.1%) | 2 (0.1%) | 9 (0.1%) | >0.999 | 9 (0.1%) | 2 (0.1%) | 7 (0.1%) | >0.999 |
| Advanced maternal age | 1,973 (17.2%) | 409 (17.3%) | 1,564 (17.1%) | 0.930 | 1,689 (17.9%) | 408 (17.3%) | 1,281 (18.1%) | 0.341 |
| Recurrent miscarriage | 42 (0.4%) | 10 (0.4%) | 32 (0.4%) | 0.750 | 35 (0.4%) | 10 (0.4%) | 25 (0.4%) | 0.780 |
| Recurrent IVF failure | 42 (0.4%) | 7 (0.3%) | 35 (0.4%) | 0.660 | 32 (0.3%) | 7 (0.3%) | 25 (0.4%) | 0.828 |
| Uterine pathology or structural abnormalities | 326 (2.8%) | 68 (2.9%) | 258 (2.8%) | 0.970 | 273 (2.9%) | 68 (2.9%) | 205 (2.9%) | 0.999 |
| Fertilization type | ||||||||
| IVF | 9,811 (85.4%) | 2,056 (86.7%) | 7,755 (85%) | 0.039 | 8,055 (85.5%) | 2,050 (86.7%) | 6,005 (85.1%) | 0.059 |
| ICSI | 1,680 (14.6%) | 315 (13.3%) | 1,365 (15%) | 1,369 (14.5%) | 315 (13.3%) | 1,054 (14.9%) | ||
| AMH (μg/L) | 4.87 [2.83, 7.27] | 4.93 [2.86, 7.35] | 4.60 [2.65, 6.95] | 0.020 | 4.73 [2.71, 6.98] | 4.59 [2.65, 6.95] | 4.75 [2.71, 6.99] | 0.968 |
| AMH <1.1 | 506 (4.4%) | 123 (5.2%) | 383 (4.2%) | <0.001 | 453 (4.8%) | 123 (5.2%) | 330 (4.7%) | 0.245 |
| 1.1 ≤AMH <4 | 3,966 (34.5%） | 879 (37.1%) | 3,087 (33.8%) | 3,404 (36.1%) | 877 (37.1%) | 2,527 (35.8%) | ||
| AMH ≥4 | 7,019 (61.1%) | 1,369 (57.7%) | 5,650 (62.0%) | 5,567 (59.1%) | 1,365 (57.7%) | 4,202 (59.5%) | ||
| AFC (n) | 20.00 [13.00, 28.00] | 20.00 [13.00, 28.00] | 19.00 [13.00, 27.00] | 0.060 | 20.00 [13.00, 27.00] | 19.00 [13.00, 27.00] | 20.00 [13.00, 27.00] | 0.809 |
| AFC <5 | 199 (1.7%) | 37 (1.6%) | 162 (1.8%) | 0.115 | 169 (1.8%) | 37 (1.6%) | 132 (1.9%) | 0.597 |
| 5 ≤AFC<15 | 3,194 (27.8%) | 698 (29.4%) | 2,496 (27.3%) | 2,790 (29.6%) | 696 (29.4%) | 2,094 (29.7%) | ||
| AFC ≥15 | 8,098 (70.5%) | 1,636 (69.0%) | 6,462 (70.9%) | 6,465 (68.6%) | 1,632 (69.0%) | 4,833 (68.5%) | ||
| Basal E2 level (pg/ml) | 39.00 [29.00, 51.00] | 45.00 [34.00, 57.00] | 37.00 [29.00, 49.00] | <0.001 | 39.00 [29.80, 51.00] | 45.00 [34.00, 57.00] | 37.00 [28.05, 49.00] | <0.001 |
| Basal FSH level (IU/L) | 7.23 [6.24, 8.43] | 7.21 [6.19, 8.43] | 7.25 [6.24, 8.43] | 0.270 | 7.26 [6.24, 8.44] | 7.21 [6.18, 8.43] | 7.28 [6.25, 8.46] | 0.116 |
| Basal LH level (mIU/ml) | 4.41 [3.26, 6.12] | 4.42 [3.26, 6.15] | 4.41 [3.26, 6.11] | 0.410 | 4.35 [3.22, 6.02] | 4.42 [3.27, 6.15] | 4.33 [3.21, 5.98] | 0.557 |
| Basal P level (ng/ml) | 0.57 [0.38, 0.83] | 0.60 [0.39, 0.84] | 0.57 [0.37, 0.83] | 0.069 | 0.58 [0.38, 0.83] | 0.60 [0.39, 0.84] | 0.57 [0.37, 0.83] | 0.475 |
| Gn starting dose (IU) | 182.20 (50.52) | 179.47 (49.94) | 182.91 (50.64) | <0.001 | 187.50 [150.00, 225.00] | 175.00 [150.00, 225.00] | 187.50 [150.00, 225.00] | <0.001 |
| 150 IU (%) | 3,955 (34.4%) | 924 (39.0%) | 3,031 (33.2%) | <0.001 | 3,147 (33.4%) | 924 (39.1%) | 2,223 (31.5%) | <0.001 |
| 225 IU (%) | 4,151 (36.1%) | 771 (32.5%) | 3,380 (37.1%) | 3,488 (37.0%) | 766 (32.4%) | 2,722 (38.6%) | ||
| Other dosage (%) | 3,385 (29.5%) | 676 (28.5%) | 2,709 (29.7%) | 2,789 (29.6%) | 675 (28.5%) | 2,114 (29.9%) | ||
| Recombinant FSH dose | 1,739.67 (652.64) | 1,739.95 (652.67) | 1,738.57 (652.66) | 0.930 | 1,752.81 (658.26) | 1,738.28 (653.02) | 1,757.68 (659.98) | 0.212 |
| Recombinant FSH duration | 9.19 (2.10) | 9.33 (1.86) | 9.15 (2.15) | <0.001 | 9.20 (2.16) | 9.34 (1.86) | 9.16 (2.25) | <0.001 |
| Recombinant LH dose | 12.74 (52.51) | 5.00 (32.00) | 14.75 (56.47) | <0.001 | 12.74 (52.51 | 4.89 (30.76) | 15.12 (56.23) | <0.001 |
| Recombinant LH duration | 0.17 (0.69) | 0.06 (0.42) | 0.20 (0.74) | <0.001 | 0.16 (0.69) | 0.05 (0.38) | 0.20 (0.74) | <0.001 |
| FSH total dose | 1,881.07 (905.464) | 1,918.29 (970.796) | 1,871.40 (887.493) | 0.033 | 1,904.54 (922.32) | 1,917.88 (971.66) | 1,900.07 (905.22) | 0.433 |
| LH total dose | 154.15 (467.35) | 184.71 (541.88) | 146.20 (445.62) | 0.001 | 164.66 (484.91) | 184.61 (541.97) | 157.98 (464.08) | 0.032 |
| HMG total dose | 141.40 (463.13) | 179.71 (539.75) | 131.44（440.52） | <0.001 | 151.73 (481.25) | 179.60 (539.83) | 142.39 (459.62) | 0.003 |
| HMG duration | 0.92 (2.52) | 1.12 (2.79) | 0.87 (2.45) | <0.001 | 0.98 (2.60) | 1.12 (2.79) | 0.94 (2.53) | 0.004 |
| GnRH-A total dose | 1.19 (0.38) | 1.15 (0.36) | <0.001 | 1.19 (0.38) | 1.14 (0.36) | <0.001 | ||
| GnRH-A duration | 4.77 (1.52) | 4.60 (1.37) | <0.001 | 4.77 (1.52) | 4.58 (1.39) | <0.001 | ||
| GnRH-a dose on Trigger day | 0.11 (0.09) | 0.10 (2.79) | 0.12 (0.09) | <0.001 | 0.11 (0.09) | 0.10 (0.09) | 0.11 (0.09) | <0.001 |
| HCG dose on Trigger day | 3,520.97 (2,390.79） | 3,559.68 (2,298.99) | 3,510.91 (2,414.11) | 0.363 | 3,579.74 (2,370.04) | 3,559.83 (2,299.74) | 3,586.41 (2,393.25) | 0.630 |
| FSH level on Trigger day (IU/L) | 12.67 [10.26, 15.95] | 12.39 [10.09, 16.14] | 12.72 [10.29, 15.90] | 0.780 | 12.72 [10.32, 16.06] | 12.39 [10.08, 16.14] | 12.80 [10.37, 16.03] | 0.228 |
| LH level on trigger Day (mIU/ml) | 2.41 [1.34, 4.17] | 2.12 [1.22, 3.54] | 2.50 [1.40, 4.37] | <0.001 | 2.40 [1.35, 4.13] | 2.12 [1.22, 3.54] | 2.50 [1.41, 4.37] | <0.001 |
| E2 level on trigger day (pg/ml) | 3,445.00 [1,923.00, 5,010.00] | 3,545.00 [2,037.00, 5,010.00] | 3,422.00 [1,891.00, 5,010.00] | 0.011 | 3,366.50 [1,864.00, 5,010.00] | 3,545.00 [2,037.00, 5,010.00] | 3,305.00 [1,806.00, 5,010.00] | <0.001 |
| P level on trigger day (ng/ml) | 1.13 [0.72, 1.60] | 1.11 [0.73, 1.57] | 1.14 [0.72, 1.61] | 0.500 | 1.13 [0.71, 1.60] | 1.11 [0.73, 1.57] | 1.13 [0.71, 1.61] | 0.979 |
| Trigger day LH ≧10 U/L | 786 (6.8%) | 117 (4.9% | 669 (7.3%) | <0.001 | 650 (6.9%) | 115 (4.9%) | 535 (7.6%) | <0.001 |
| Trigger day LH/Gn day LH ≥ 2 | 934 (8.1%) | 147 (6.2%) | 787 (8.6%) | <0.001 | 797 (8.5%) | 145 (6.1%) | 652 (9.2%) | <0.001 |
| Endometrial morphology on hCG day | ||||||||
| A | 7,020 (61.1%) | 1,569 (66.2%) | 5,451 (59.8%) | <0.001 | 5,806 (61.6%) | 1,565 (66.2%) | 4,241 (60.1%) | <0.001 |
| B | 2,868 (25.0%) | 499 (21.0%) | 2,369 (26.0%) | 2,334 (24.8%) | 497 (21.0%) | 1,837 (26.0%) | ||
| C | 704 (6.1%) | 126 (5.3%) | 578 (6.3%) | 573 (6.1%) | 126 (5.3%) | 447 (6.3%) | ||
| ELSE | 899 (7.8%) | 177 (7.5%) | 722 (7.9%) | 711 (7.5%) | 177 (7.5%) | 534 (7.6%) | ||
| Endometrial Thickness(mm) | 9.00 [8.00, 11.00] | 9.00 [8.00, 11.00] | 9.00 [8.00, 11.00] | 0.011 | 9.00 [8.00, 11.00] | 9.00 [8.00, 11.00] | 9.00 [8.00, 11.00] | 0.010 |
| Number of embryos for ET | ||||||||
| 1 embryo | 4,067 (35.4%) | 817 (34.5%) | 3,250 (35.6%) | 0.296 | 3,353 (35.58%) | 673 (28.46%) | 2,680 (37.77%) | 0.197 |
| 2 embryo | 7,424 (64.6%) | 1,554 (65.5%) | 5,870 (64.4%) | 6,121 (64.95%) | 1,290 (54.95%) | 4,831 (68.09%) | ||
| Embryo stage | ||||||||
| D3 | 432 (3.8%) | 102 (4.3%) | 330 (3.6%) | 0.192 | 354 (3.8%) | 102 (4.3%) | 252 (3.6%) | 0.272 |
| D5/D6 | 3,633 (31.6%) | 715 (30.2%) | 2,918 (32.0%) | 2,932 (31.1%) | 713 (30.1%) | 2,219 (31.4%) | ||
| D3 + D3 | 2,410 (21.0%) | 522 (22.0%) | 1,888 (20.7%) | 2,008 (21.3%) | 521 (22.0%) | 1,487 (21.1%) | ||
| D3 + D5/D6 | 142 (1.2%) | 26 (1.1%) | 116 (1.3%) | 122 (1.3%) | 25 (1.1%) | 97 (1.4%) | ||
| D5/D6 + D5/D6 | 4,870 (42.4%) | 1,006 (42.4%) | 3,864 (42.4%) | 4,006 (42.5%) | 1,004 (42.5%) | 3,002 (42.5%) | ||
| ELSE | 4 (0.0%） | 0 | 4 (0.0%） | 2 (0.0%) | 0 (0.0%) | 2 (0.0%) | ||
| Male information | ||||||||
| Male age | 32.00 [29.00, 35.00] | 32.00 [30.00, 36.00] | 32.00 [29.00, 35.00] | 0.050 | 32.00 [29.00, 35.00] | 32.00 [30.00, 36.00] | 32.00 [29.00, 35.00] | 0.192 |
| Abnormal semen analysis | 6,803 (59.2%) | 1,436 (60.6%) | 5,367 (58.8%) | 0.140 | 5,592 (59.3%) | 1,431 (60.5%) | 4,161 (58.9%) | 0.189 |
| DFI（%） | 12.70 [8.55, 19.72] | 12.67 [8.21, 19.72] | 12.71 [8.61, 19.73] | 0.680 | 12.80 [8.56, 19.74] | 12.64 [8.18, 19.72] | 12.85 [8.64, 19.76] | 0.534 |
| DFI<30 | 10,540 (91.7%) | 2,167 (91.4%) | 8,373 (91.8%) | 0.540 | 8,645 (91.7%) | 2,162 (91.4%) | 6,483 (91.8%) | 0.546 |
| DFI≥30 | 951 (8.3%) | 204 (8.6%) | 747 (8.2%) | 779 (8.3%) | 203 (8.6%) | 576 (8.2%) | ||
| OHSS | 113 (1.0%) | 11 (0.4%) | 102 (1.1%) | 0.006 | 87 (0.9%) | 10 (0.4%) | 77 (1.1%) | 0.010 |
| Early-onset OHSS | 73 (0.6%) | 9 (0.3%) | 64 (0.7%) | 0.061 | 58 (0.6%) | 8 (0.3%) | 50 (0.7%) | 0.060 |
| Late-onset OHSS | 40 (0.3%) | 2 (0.1%) | 38 (0.4%) | 29 (0.3%) | 2 (0.1%) | 27 (0.4%) | ||
| Degree of OHSS | ||||||||
| Mild | 53 (0.5%) | 4 (0.1%) | 49 (0.5%) | 0.091 | 43 (0.5%) | 4 (0.2%) | 39 (0.6%) | 0.079 |
| Moderate | 36 (0.3%) | 4 (0.1%) | 32 (0.4%) | 25 (0.3%) | 4 (0.2%) | 21 (0.3%) | ||
| Severe | 24 (0.2%) | 3 (0.1%) | 21 (0.2%) | 19 (0.2%) | 2 (0.1%) | 17 (0.2%) | ||
PSM, propensity score matching; BMI, body mass index; IVF, in vitro fertilization; ICSI, intracytoplasmic sperm injection; AMH, anti-Mullerian hormone; FSH, follicular stimulating hormone; LH, luteinizing hormone; AFC, antral follicle counting; HMG, human menopausal gonadotropin; D3, cleavage-stage embryo; D5/D6/ELSE, blastocyst; OHSS, ovarian hyperstimulation syndrome.