Highlights from PCRS 2015: BMI's Effect on the Uterine Lining

Posted on May 15, 2015 by Inception Fertility

In the last issue of the Fertility Flash Newsletter, we reported on a number of studies linking higher body weight to the decreased success of in vitro fertilization (IVF). These were presented at the Annual Meeting of the American Society for Reproductive Medicine (ASRM). The conversation continued at the 2015 Annual Meeting of the Pacific Coast Reproductive Society (PCRS) in March with the presentation of more papers on the topic.

A common culprit?

Dr. Ionna A. Comstock and colleagues at Stanford, CA and Valencia, Spain recently explored this topic, reporting on the impact of body mass index (BMI) on endometrial receptivity in infertile patients. The study earned the authors 1st Place in the PCRS Outstanding Paper Awards.

The researchers found that the incidence of a non-receptive endometrium was 27 percent higher in obese women—those with a BMI of 30 to 40—and 50 percent higher in morbidly obese women—those with a BMI greater than 40—compared with overweight women or women of normal weight.

Gene analysis. The researchers used the Endometrial Receptive Array (ERA) test, the first of its kind to assess expression of genes that affect the endometrial lining. The ERA analysis evaluates 238 genes, and the test involves having an endometrial biopsy, which is similar to having a Pap test. In the study, samples were taken from 23 women.

The researchers analyzed which of 238 gene pathways were dysregulated in obese women with a non-receptive endometrium. In these women, which genes are responsible for affecting the window of implantation (WOI)? Data from the study point to a subset of genes in endometrial alteration, which reinforces that insulin secretion and other obesity-related pathways may be responsible.

This study provides further insight into the endometrium’s role in IVF success. Yes, the quality of the ovum and embryo remains critical, but the receptivity of a woman’s uterus also plays an important role. Altered gene expression in obese women may lead to a dysfunctional endometrium. This message is important for women who are carrying a lot of extra weight.


1. Comstock IA et al. Fertility & Sterility. Vol. 103, No.2, Supplement, February 2015.

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