Even in the best-case scenario, when fertility clinics transfer chromosomally normal embryos into a would-be mother’s uterus, the procedure only leads to a live birth half of the time. Some embryo transfers result in a pregnancy, and then miscarriage; but in 30 to 35% of cases, the embryo doesn’t even implant in the uterus.
For decades, fertility research has focused intensely on embryo quality, but some scientists have begun to suspect that the overlooked problem lies in the uterus itself. New research from Rutgers Health and Michigan State University supports that view. The study in JCI Insight identified 556 genes, concentrated in gland cells in the uterine lining (endometrium), that are increased in fertile women – but not in those who have struggled with infertility – when the uterus enters its brief window of receptivity.
“This was one of the first attempts to really look at the menstrual cycle in women who are fertile and try and understand how the endometrium is changing, how it becomes briefly receptive to embryo attachment at the most fundamental level,” said Nataki Douglas, an associate professor of obstetrics, gynecology and reproductive health at Rutgers New Jersey Medical School and senior author of the study.
The researchers couldn’t sample endometrial tissue just before the embryo transfer after in vitro fertilization and compare samples from patients whose treatments did and didn’t succeed, as such procedures could disrupt early pregnancy and create failures. To read the full story.