Biochemist Discovers New Clues to Infertility in Study on Cholesterol

The study “reinforces the potential for cholesterol to be an important determinant in fertility and pregnancy,” notes Browne, who collaborated with researchers from the Eunice Kennedy Shriver National Institute of Child Health and Human Development and Emory University.

The study, assessing 500 couples, revealed that on average, couples who did not achieve pregnancy within a year of trying had the highest cholesterol levels.

When the woman had high cholesterol levels but the man did not, pregnancy also was difficult to achieve.

“While high levels of total cholesterol were significant predictors of infertility, the study revealed that the free cholesterol component  was an even more powerful indicator of infertility,” says Browne.

Free cholesterol — not measured in routine blood tests — is a component of total cholesterol, which is routinely measured on standard blood tests.

Previously, Browne was part of a team that discovered the importance of HDL cholesterol — or ‘good’ cholesterol — in the follicular fluid surrounding the developing egg in the ovary.

“We found that the higher the levels of HDL cholesterol, the more likely it was that in vitro fertilization (IVF) would result in a healthy embryo,” says Browne. 

By contrast, lower levels of HDL increased the chances of embryo fragmentation, which is detrimental to embryo health and a major problem during IVF.

“With IVF resulting in healthy babies 30 to 40 percent of the time at best,” says Browne, “we are highly motivated to better understand how follicular fluid parameters may help to predict IVF success or failure.”

Browne collaborated with researchers at the University of California at San Francisco and the University at Albany to conduct the pilot studies of women undergoing IVF.

Building off the pilot studies, Browne and his co-authors measured the levels of various HDL-particle components in two ovarian follicles in each of 171 women undergoing IVF.

They found that the variability in these components was often greater within each woman than between different women, suggesting that each ovarian follicle is an independent micro-environment for the developing egg.

The extent of that variability seemed to correlate with demographic and lifestyle factors — such as age, body mass and cigarette use — suggesting that some of these influences may be modified through lifestyle changes.

The study, Variability in the Components of High-Density Lipoprotein Particles Measured in Human Ovarian Follicular Fluid: A Cross-Sectional Analysis, was published in Fertility and Sterility.

The current study, Lipid Concentrations and Couple Fecundity: The LIFE Study, has been published in the Journal of Clinical Endocrinology and Metabolism.

The paper is part of a series associated with the National Institutes of Health-funded Longitudinal Investigation of Fertility and the Environment study.