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Table 3 Stepwise Cox regression analysis on live birth probability of ART clinical pregnancies

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

Variables βa SEb HR 95% CI P
Maternal age (reference: <30)
 30–35 0.0733 0.1102 1.08 0.87–1.34 0.506
 36–40 0.3758 0.1697 1.46 1.04–2.03 0.027 *
  > 40 1.1000 0.3222 3.00 1.60–5.65 <0.001 *
COH protocol (reference: GnRH-a long protocol)
 GnRH-a short protocol 0.0326 0.1191 1.03 0.82–1.30 0.784
 GnRH antagonist protocol 0.8914 0.2698 2.44 1.44–4.14 <0.001 *
 Minimal stimulation protocol 0.7869 0.2152 2.20 1.44–3.35 <0.001 *
 GnRH-a rolonged protocol −0.1192 0.4160 0.89 0.39–2.01 0.774
 Other protocol 1.3692 0.5070 3.93 1.46–10.62 0.007 *
Cycle Type (reference: Fresh)
 Frozen 0.2296 0.1057 1.26 1.02–1.55 0.030 *
Serum hCG levels 14 days after transfer (reference: < 695.30)
  ≥ 695.30 −1.0848 0.1180 0.34 0.27–0.43 <0.001 *
  1. HR hazard ratio, CI confidence interval
  2. aβ is the estimated parameter of the regression model
  3. bSE is the standard error of the regression model