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Table 4 Comparison of early miscarriage and late miscarriage in ART clinical pregnancies

From: Influencing factors of pregnancy loss and survival probability of clinical pregnancies conceived through assisted reproductive technology

Variables Early miscarriage Late miscarriage
Nc (%) n (%) HR (95%CI)a P a Nd (%) n (%) HR (95%CI)a P a
Maternal age
  < 30 2556(47.0) 180(39.5) 1.00   2376(47.7) 94(49.7) 1.00  
 30–35 2361(43.4) 188(41.2) 1.14(0.93–1.40) 0.215 2173(43.6) 80(42.3) 0.93(0.69–1.25) 0.630
 36–40 472(8.7) 69(15.1) 2.14(1.62–2.83) <0.001 * 403(8.1) 15(7.9) 0.94(0.54–1.62) 0.823
  > 40 53(1.0) 19(4.2) 6.04(3.76–9.69) <0.001 * 34(0.7) 0(0.0) 0 0.992
Maternal BMI
  < 18.5 509(9.4) 32(7.0) 0.82(0.57–1.18) 0.282 477(9.7) 15(8.1) 0.82(0.52–1.51) 0.647
 18.5–25 4009(74.3) 335(73.3) 1.00   3674(74.4) 130(70.3) 1.00  
 25–28 641(11.9) 65(14.2) 1.19(0.91–1.55) 0.205 576(11.7) 24(13.0) 1.20(0.78–1.86) 0.407
 ≥28 235(4.4) 25(5.5) 1.35(0.90–2.03) 0.145 210(4.3) 16(8.6) 2.09(1.22–3.57) 0.007 *
Paternal BMI
  < 18.5 103(1.9) 8(1.8) 1.07(0.53–2.16) 0.859 95(1.9) 1(0.5) 0.00(0.00 − +∞) 0.992
 18.5–25 3309(61.7) 266(58.6) 1.00   3043(62.0) 120(64.9) 1.00  
 25–28 1344(25.1) 129(28.4) 1.17(0.95–1.45) 0.137 1215(24.8) 50(27.0) 1.06(0.76–1.48) 0.728
  ≥ 28 603(11.3) 51(11.2) 1.08(0.80–1.46) 0.616 552(11.3) 14(7.6) 0.64(0.37–1.12) 0.118
Infertility type
 Primary 2781(53.0) 227(51.1) 1.00   2554(53.2) 92(51.7) 1.00  
 Secondary 2466(47.0) 217(48.9) 0.94(0.78–1.14) 0.544 2249(46.8) 86(48.3) 1.10(0.81–1.49) 0.538
COH protocolb
 GnRH-a long protocol 3406(63.1) 243(53.4) 1.00   3163(64.0) 125(67.9) 1.00  
 GnRH-a short protocol 1573(29.2) 132(29.0) 1.00(0.80–1.26) 0.974 1441(29.2) 48(26.1) 0.85(0.60–1.21) 0.370
 GnRH antagonist protocol 95(1.8) 29(6.4) 4.11(2.78–6.08) <0.001 * 66(1.3) 5(2.7) 1.95(0.80–4.78) 0.144
 Minimal stimulation protocol 186(3.4) 40(8.8) 2.39(1.67–3.43) <0.001 * 146(3.0) 1(0.5) 0.18(0.02–1.29) 0.088
 GnRH-a rolonged protocol 123(2.3) 8(1.8) 0.90(0.44–1.82) 0.765 115(2.3) 3(1.6) 0.67(0.21–2.11) 0.492
 Other protocol 13(0.2) 3(0.7) 3.27(1.04–10.23) 0.042 * 10(0.2) 2(1.1) 5.52(1.36–22.40) 0.017 *
The total Gn dose
  < 1808.01 3181(59.0) 252(55.4) 1.00   2929(59.4) 104(56.2) 1.00  
  ≥ 1808.01 2208(41.0) 203(44.6) 1.08(0.89–1.30) 0.440 2005(40.6) 81(43.8) 1.15(0.86–1.54) 0.355
Fertilization methods
 IVF 4543(83.9) 386(84.6) 1.00   4157(83.8) 162(86.6) 1.00  
 ICSI 875(16.1) 70(15.4) 0.93(0.72–1.20) 0.562 805(16.2) 25(13.4) 0.81(0.53–1.23) 0.320
Cycle type
 Fresh 2675(51.9) 161(39.1) 1.00   2514(53.0) 106(60.6) 1.00  
 Frozen 2477(48.1) 251(60.9) 1.67(1.37–2.04) <0.001 * 2226(47.0) 69(39.4) 0.73(0.54–0.99) 0.045 *
No. of embryos transferred
 1 474(8.7) 64(14.0) 1.00   410(8.2) 16(8.4) 1.00  
 2 4324(79.6) 330(72.1) 0.61(0.47–0.80) <0.001 * 3994(80.2) 157(82.6) 0.99(0.59–1.65) 0.961
 3 637(11.7) 64(14.0) 0.63(0.44–0.89) 0.010 * 573(11.5) 17(8.9) 0.75(0.38–1.51) 0.425
Cleavage-stage embryo or blastocystb
 Cleavage-stage embryo 3860(73.3) 305(68.2) 1.00   3555(73.8) 135(73.8) 1.00  
 Blastocyst 1405(26.7) 142(31.8) 1.15(1.04–1.27) 0.006 * 1263(26.2) 48(26.2) 1.00(0.85–1.18) 0.994
Serum hCG levels 14 days after transfer
  < 695.30 2187(52.2) 248(82.7) 1.00   1939(49.8) 79(59.8) 1.00  
  ≥ 695.30 2006(47.8) 52(17.3) 0.22(0.16–0.30) <0.001 * 1954(50.2) 53(40.2) 0.68(0.48–0.96) 0.030 *
  1. aAdjusted for maternal age
  2. bGnRH antagonist protocol was not utilized in Changzhou, and they only transferred cleavage-stage embryos
  3. cthe number of clinical pregnancies
  4. dthe number of clinical pregnancies after 12 weeks of gestational age