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Table 3 Estimated cumulative probabilities of live birth and corresponding hazard ratios of failing at ART by discrete smoking patterns (EARTH study, N = 225 couples, 354 ART cycles)

From: Discrete survival model analysis of a couple’s smoking pattern and outcomes of assisted reproduction

 

Number of Couples/Cycles

Estimated cumulative probability of live birth, per 100 cyclesa

Adjusted Hazard Ratio (95% CI)b

P-Valueb

Female Smoking History

   

0.24

 Never Smoker

167/249

54.2 (45.8, 64.0)

1.00 (REF)

 

 Ever Smoker

58/105

45.0 (32.8, 61.8)

1.30 (0.84, 2.02)

 

Female Smoking Status

   

0.35

 Never Smoker

167/249

54.1 (45.7, 63.9)

1.00 (REF)

 

 Former Smoker

51/93

46.9 (34.5, 63.9)

1.23 (0.79, 1.91)

 

 Current Smoker

7/12

22.7 (5.6, 92.0)

2.43 (0.64, 9.39)

 

Male Smoking History

   

0.93

 Never Smoker

154/235

54.0 (46.6, 68.4)

1.00 (REF)

 

 Ever Smoker

71/119

53.2 (43.1, 65.7)

1.02 (0.64, 1.63)

 

Male Smoking Status

   

0.75

 Never Smoker

154/235

54.3 (45.7, 64.6)

1.00 (REF)

 

 Former Smoker

55/89

56.4 (44.6, 71.5)

0.94 (0.55, 1.61)

 

 Current Smoker

16/30

46.7 (30.6, 72.7)

1.25 (0.69, 2.25)

 

Couples Ever Smoking Status

   

0.59

 Female and Male Never Smokers

121/172

54.7 (45.7, 65.4)

1.00 (REF)

 

 Female Never Smoker, Male Ever Smoker

46/77

50.7 (38.4, 67.0)

1.12 (0.69, 1.84)

 

 Female Ever Smoker, Male Never Smoker

33/63

42.2 (28.7, 62.0)

1.43 (0.85, 2.41)

 

 Female and Male Ever Smokers

25/42

47.5 (31.8, 70.8)

1.24 (0.62, 2.46)

 
  1. All estimates were calculated from a discrete time Cox proportional Hazard models adjusting for female age (centered continuous) and BMI (continuous); induction protocol (categorical); female educational status (categorical); centered pack-years history (centered continuous) and partner’s smoking status (categorical)
  2. aEstimates of cumulative probability of not failing ART cycle are given for the average couple in our cohort (e.g. female age (34.8 years) and BMI (23.8 kg/m2); induction protocol (luteal agonist); female educational status (more than college); centered pack-years history (0.93 packs-years for women; 2.47 packs-years for men) and partner’s smoking status (never smoker)
  3. b P-Value is testing for any difference across categories of exposure