The study, “Effect of Natural Cycle Endometrial Preparation for Frozen-Thawed Embryo Transfer in Patients with Advanced Endometriosis,” also showed that the outcome of the pregnancy is not affected by the severity of the endometriosis or the presence of an active endometrial cyst.
A team of researchers led by Dr. Yanping Kuang of the Department of Assisted Reproduction at Shanghai Ninth People’s Hospital in China recruited 179 patients with moderate to severe endometriosis who underwent 233 frozen-thawed embryo transfer (FET) cycles between March 2011 and August 2013. They also recruited 258 patients with tubal factor infertility who underwent 300 FET cycles, as a control group.
FET is a technique where additional embryos left from an IVF (in vitro fertilization) cycle are frozen so they can be used in the future. It can be used to treat infertility caused by endometriosis or other conditions.
The researchers recorded the rates of implantation, clinical pregnancy, live birth, ongoing pregnancy, miscarriage, and pregnancy complications among women in both groups.
The results showed that the rate of implantation was 36% in women with endometriosis and 30.4% in those with tubal factor infertility. The pregnancy rate was 50.2% and 45.3% in the two groups of women, respectively. Finally, the live birth rates were 40% in women with endometriosis and 39% in those with tubal factor infertility.
Researchers did not observe any differences in ongoing pregnancy rates, miscarriage, and pregnancy complications associated with the severity of endometriosis. They also did not find any congenital birth defects.
Although severe endometriosis did not affect the birth rate, researchers observed higher frequencies of premature birth among women in both groups. This was an average of 37 weeks for women with endometriosis and 38.3 weeks for those with tubal factor infertility. Similarly, they observed a low birth weight of less than 2.5 kilograms in 26.4% of cases for women with endometriosis and 16.6% of cases for women with tubal factor infertility.
The authors concluded that pregnancy outcomes are similar between women with advanced endometriosis and tubal factor infertility following FET.