9 March 2009

More evidence for obesity-infertility link

by Kate Melville

Obese women appear to undergo alterations in their ovaries which might be responsible for an egg's inability to make an embryo, according to a new study in the Journal of Clinical Endocrinology & Metabolism.

It has been documented in the past that obese women trying to become pregnant take longer to conceive, even if they are young and have a regular menstrual cycle. The new study sought to determine if there are alterations in an egg's environment in obese women which contribute to poorer reproductive outcomes.

"Characteristics of eggs are influenced by the environment in which they develop within the ovary," said the study's lead author Rebecca Robker, from Adelaide University in Australia. "Our study found that obese women have abnormally high levels of fats and inflammation in the fluid surrounding their eggs which can impact an egg's developmental potential."

In the study, Dr. Robker and her colleagues measured hormone and metabolite levels in follicular fluid obtained from the subjects' ovaries during their egg collection procedures. They found that obese women exhibited an altered ovarian follicular environment, particularly increased metabolite and androgen activity levels, which may be associated with poorer reproductive outcomes.

The researchers say that the fats might alter the very sensitive metabolism of the egg and such changes are known to be harmful to embryo formation. In addition, inflammation can damage cells and when this happens to eggs it can affect embryo survival.

"Obesity is well known to cause changes in blood lipids and heightened inflammation which detrimentally affects a person's general health," concluded Dr. Robker. "Our research shows that obesity similarly changes the environment in the ovary which bathes and nourishes a woman's developing eggs."

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Source: The Endocrine Society