Table 1.
Basic characteristics of the patients and embryos undergoing ART treatment
| Variables | Singletons | Singletons from twin gestation | Twins from twin gestation | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Male | Female | P | Male | Female | P | Male | Female | P | |
| Infertility type (n, %) | 0.009 | 0.524 | 0.959 | ||||||
| Primary | 1018(53.4) | 890(46.6) | 163(56.0) | 128(44.0) | 1182(52.1) | 1086(47.9) | |||
| Secondary | 947(57.7) | 694(42.3) | 159(58.7) | 112(41.3) | 1028(52.6) | 928(47.4) | |||
| Infertility factor (n, %) | 0.463 | 0.791 | 0.278 | ||||||
| Male | 1324(56.0) | 1042(44.0) | 225(57.7) | 165(42.3) | 1564(53.0) | 1388(47.0) | |||
| Female | 314(55.3) | 254(44.7) | 46(59.0) | 32(41.0) | 296(48.7) | 312(51.3) | |||
| Both male and female | 327(53.2) | 288(46.8) | 51(54.3) | 43(45.7) | 350(52.7) | 314(47.3) | |||
| Maternal age group (n, %) | 0.085 | 0.230 | 0.823 | ||||||
| ≤35 | 1748(54.9) | 1437(45.1) | 286(58.2) | 205(41.8) | 2102(52.3) | 1914(47.7) | |||
| >35 | 217(59.6) | 147(40.4) | 36(50.7) | 35(49.3) | 108(51.9) | 100(48.1) | |||
| Paternal age group (n, %) | 0.019 | 0.968 | 0.864 | ||||||
| ≤30 | 519(52.5) | 470(47.5) | 85(55.9) | 67(44.1) | 717(52.0) | 663(48.0) | |||
| 31–331 | 545(56.6) | 418(43.4) | 83(58.5) | 59(41.5) | 418(51.2) | 398(48.8) | |||
| 34–362 | 424(53.5) | 368(46.5) | 86(58.1) | 62(41.9) | 547(53.4) | 477(46.6) | |||
| ≥373 | 477(59.3) | 328(40.7) | 68(56.7) | 52(43.3) | 528(52.7) | 476(47.3) | |||
| Age difference (n, %) | 0.675 | 0.330 | 0.093 | ||||||
| Older mother | 302(53.7) | 260(46.3) | 46(55.4) | 37(44.6) | 304(49.4) | 312(50.6) | |||
| Older father | 1400(55.8) | 1110(44.2) | 239(59.0) | 166(41.0) | 1601(53.2) | 1411(46.8) | |||
| None | 263(55.1) | 214(44.9) | 37(50.0) | 37(50.0) | 305(51.2) | 291(48.8) | |||
| Fertilization method (n, %) | 0.526 | 0.186 | 0.238 | ||||||
| IVF | 1178(56.2) | 919(43.8) | 201(59.3) | 138(40.7) | 1394(52.1) | 1280(47.9) | |||
| ICSI | 298(55.1) | 243(44.9) | 29(46.8) | 33(53.2) | 252(48.5) | 268(51.5) | |||
| FET | 455(53.9) | 389(46.1) | 89(57.8) | 65(42.2) | 522(54.7) | 432(45.3) | |||
| Maternal BMI (n, %) | 0.284 | 0.805 | 0.359 | ||||||
| <18.5 | 275(52.5) | 249(47.5) | 37(54.4) | 31(45.6) | 308(50.5) | 302(49.5) | |||
| 18.5–23.9 | 1351(56.2) | 1054(43.8) | 228(58.2) | 164(41.8) | 1530(52.4) | 1390(47.6) | |||
| ≥24 | 339(54.7) | 281(45.3) | 57(55.9) | 45(44.1) | 372(53.6) | 322(46.4) | |||
| Type of cycle (n, %) | 0.332 | 0.884 | 0.240 | ||||||
| Fresh | 1510(55.8) | 1195(44.2) | 233(57.1) | 175(42.9) | 1688(51.6) | 1582(48.4) | |||
| Frozen | 454(53.9) | 388(46.1) | 89(57.8) | 65(42.2) | 522(54.7) | 432(45.3) | |||
| Embryo transfer stage (n, %) | 0.378 | 0.638 | 0.002 | ||||||
| Cleavage stage | 1694(55.0) | 1387(45.0) | 255(58.1) | 184(41.9) | 1741(50.8) | 1685(49.2) | |||
| Blastocyst | 227(57.3) | 169(42.7) | 64(55.7) | 51(44.3) | 424(58.1) | 306(41.9) | |||
| Usage of Gn (IU/L, M (P25, P75)) | 2100(1500, 2775) | 2025(1462.4, 2850) | 2062.5(1575, 2700) | ||||||
| Days of Gn use (day, M (P25, P75)) | 12(11, 13) | 12(11, 13) | 12(11, 13) | ||||||
ART Assisted reproductive technology, ICSI Intracytoplasmic sperm injection, IVF In vitro fertilization, FET Frozen embryo transfer, Gn Gonadotropin, BMI Body mass index
1Singletons from twin gestation and twins from twin gestation were classified as 31–33 and 31–32, respectively
2Singletons from twin gestation and twins from twin gestation were classified as 34–37 and 33–35, respectively
3Singletons from twin gestation and twins from twin gestation were classified as ≥ 38 and ≥ 36, respectively