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Table 2 Baseline clinical characteristics of study patients

From: Assisted hatching of vitrified-warmed blastocysts prior to embryo transfer does not improve pregnancy outcomes

  Assisted Hatched (n = 1986) Non-Assisted Hatched (n = 179) P-valueª
Mean maternal age at retrieval 33.8 ± 3.9 33.1 ± 3.7 0.03
Mean maternal age at transfer 35.3 ± 4.0 34.6 ± 4.0 0.02
Cause of infertility
 Ovulatory disorder 14.2% (283) 17.9% (32) 0.18
 Tubal factor 30.5% (606) 32.3% (58) 0.54
 Endometriosis 7.0% (139) 7.3% (13) 0.89
 Male Factor 34.5% (686) 34.1% (62) 0.97
 Other 30.4% (604) 24.7% (45) 0.16
Endometrial preparation protocol
 Natural Cycle 11.2% (223) 13.7% (25) 0.31
 Hormone Replacement Therapy 88.8% (1764) 86.0% (154) 0.31
Number of embryos transferred per cycle
 1 74.1% (1474) 69.8% (125) 0.24
 2 25.5% (506) 30.2% (54) 0.16
 3 0.3% (6) 0.0% (0) 0.91
 4 0.1% (2) 0.0% (0) 0.61
Previous transfers (Fresh & Vitrified-warmed)
 0 14.4% (287) 13.7% (25) 0.80
 1 34.8% (692) 34.6% (63) 0.97
 2 22.5% (444) 17.2% (37) 0.08
 3 13.5% (269) 13.7% (23) 0.24
  > 4 15.0% (296) 16.8% (31) 0.40
  1. ªP values are for comparisons of continuous (t test) or categorical (chi-square test) variables between the two groups