BUFFALO, N.Y. – A study of 500 couples trying to conceive
a baby has revealed that higher levels of cholesterol reduce their
chances of conceiving a healthy embryo.
University at Buffalo biochemist Richard W. Browne, PhD, is a
co-author on this research, one of a series of publications
involved in the National Institutes of Health-funded Longitudinal
Investigation of Fertility and the Environment (LIFE) study.
“This study reinforces the potential for cholesterol to be
an important determinant in fertility and pregnancy,” says
Browne, an associate professor in the Department of Biotechnical
and Clinical Laboratory Sciences in the UB School of Medicine and
Lead author on the paper is Enrique Schisterman, PhD, chief of
the Epidemiology Branch at the Eunice Kennedy Shriver National
Institute of Child Health and Human Development (NICHD); co-authors
are Sunni L. Mumford, Zhen Chen and Germaine L. Buck-Louis, all
from NICHD, and Dana Boyd Barr of Emory University.
The current study, published online in the Journal of
Endocrinology and Metabolism, revealed that, on average, couples
who did not achieve pregnancy within a year of trying, had the
highest cholesterol levels. Difficulty achieving pregnancy also was
associated with couples in which the woman had high cholesterol
levels but the man did not.
The NICHD release is here.
The study measured ‘free’ and total cholesterol
levels in the blood. Free cholesterol – which is not measured
in routine blood tests – is a component of total cholesterol,
which is routinely measured on standard blood tests.
“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.
Browne’s interest in women’s health and fertility
began with his work on the NIH-funded BIOcycle study, with
colleagues in the UB School of Public Health and Health
Professions, led by Schisterman and NICHD. In that project,
scientists examined lipids, lipoproteins and oxidative stress and
its effect on women throughout the menstrual cycle.
Those studies demonstrated unique fluctuations in lipid and
lipoprotein metabolism in women, particularly as it relates to the
Browne then teamed up with Victor Y. Fujimoto of the University
of California at San Francisco and Michael Bloom of the University
at Albany to do pilot studies of women undergoing in vitro
“We then decided to look at the cholesterol within a
woman’s ovarian follicle,” says Browne.
They discovered that HDL cholesterol was particularly important in
the follicular fluid, the fluid compartment that surrounds and
bathes the developing oocyte (egg) within the ovary.
“We found that the higher the levels of good cholesterol,
or HDL, the more likely it was that IVF would result in a healthy
embryo,” says Browne. By contrast, he said, lower levels of
HDL increased the chances of embryo fragmentation, which is
detrimental to embryo health and a major problem during IVF.
These pilot studies were the impetus for a more comprehensive
study of follicular fluid components and IVF outcomes. Last month,
Browne and his co-authors, led by Bloom, reported on HDL particles
in follicular fluid.
The study involved the collection of follicular fluid from two
ovarian follicles in each of 171 women undergoing IVF. Levels of
various HDL-particle components in the follicles were measured in
Browne’s laboratory at UB.
The researchers found that the variability in these components
within each woman was often greater than the variability between
different women. This suggests that each ovarian follicle appears
to be an independent micro-environment for the developing egg.
The extent of that variability seemed to correlate with
demographic factors, such as age, body mass and cigarette smoking
of the woman, meaning there is the potential to modify these
influences through lifestyle changes.
“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.”
Bloom was lead author on that paper, published in Fertility and
Sterility, with co-authors Fujimoto and UAlbany doctoral candidate
Keewan Kim in addition to Browne. The research was supported by the
National Institute on Aging of the NIH.