"Body weight and infertility linked"

Body weight and infertility linked

Penelope Debelle, Adelaide

The Age, Australia
August 24, 2007

RESEARCH has confirmed the empirical link between obesity and infertility by showing the "fat eggs" of obese women do not develop into healthy embryos.

The eggs were damaged by high levels of fat and cholesterol, which made diet a key factor in infertility, according to research by PhD student Cadence Minge from the Adelaide University Research Centre for Reproductive Health. The eggs of female mice, which were fed a high-fat diet that made them insulin-resistant and pre-diabetic, were harvested and grown in vitro but were unable to develop into healthy embryos. "They were much slower to divide and grow," Ms Minge said. "And the way that the cells developed was also disturbed."

Ms Minge said scientists were yet to understand exactly why the "fat eggs" were infertile and how they were damaged. But her research had established that a protein in cells that surrounded and nourished the egg was linked to the induced fertility and its effect could be reversed by using an anti-diabetic drug such as rosiglitazone (marketed as Avandia). The drug activated the protein that helped the egg to mature before its release so that normal embryo development function was restored. However, Ms Minge said the drug had side effects and was not advocated as "a quick fix" for infertile women.

"The rosiglitazone findings are of great significance for scientists researching egg maturation within the ovary. But at this stage, the research findings have only been made in mice," she said. "Also, the drug itself can have possible harmful side effects and more research is needed to find other, safer ways of activating the protein." She said weight loss was by far the most effective way to restore fertility and even shedding five to 10 kilograms was enough to trigger ovulation in obese women who had ceased to ovulate.