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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