Kimberly Liu et al., from Toronto, Canada, now have reviewed over 40,000 fresh and frozen IVF cycles. They show that live birth rates decreased and pregnancy loss rates increased with each millimeter decline of endometrial thickness below 8 mm in fresh transfer cycles. In frozen transfer cycles, live birth rates decreased below 7mm, but no significant difference in pregnancy loss rates was found. The likelihood of achieving an endometrial thickness over 8 mm decreased with age. Yet, live birth rates remained fair (15-21%) in patients with an endometrial thickness of 5-6 mm in fresh and 4-6 mm in frozen cycles. Data were ‘suppressed and not available’ for 49 embryo transfers in women with an endometrium below 4 mm.
JLH (Hans) Evers, Editor-in-Chief Human Reproduction