Infertility and obesity go together for some women

Aug 27 2007

An Australian scientist says she has discovered scientific evidence that obesity is a key factor in infertility because of how it affects a woman's eggs.

It has for some time been suspected that obesity may be a major factor in why some couples' fail to conceive, but until now the effects of obesity on the egg were a mere suspicion.

The findings by the University of Adelaide researcher were made in a study using female mice.

PhD student Cadence Minge at the University's Research Centre for Reproductive Health found that consuming a diet high in fat causes damage to eggs stored in female ovaries; as a result, when fertilised these eggs are not able to undergo normal, healthy development into embryos.

Her research has also discovered a way to completely reverse the effects of obesity on mouse eggs, enabling afflicted eggs to develop into healthy embryos.

Ms Minge has discovered that a protein in the cells surrounding, supporting and nourishing the egg - called Peroxisome Proliferator-Activated Receptor gamma (PPARã) - is the main reason behind diet-induced infertility.

Ms Minge says the behaviour of this protein helps to determine the way in which the ovaries sense and respond to fats, and being able to control this protein will be very important in the search to reverse infertility caused by poor diets.

Ms Minge's research has found that when the protein is selectively targeted with the anti-diabetes drug rosiglitazone (Avandia), the adverse effects of obesity on egg quality are completely reversed.

Ms Minge says the drug enables us to switch on the protein, thereby changing the way in which the ovaries sense and respond to fats; embryo development rates are restored, and the cellular differentiation of the early embryo is improved.

She says in the long-term these improvements can result in increased birth weight and fetal survival but she does warn that rosiglitazone should not be seen as a "quick fix" for infertile women.

Ms Minge says though the findings are of great significance for scientists researching egg maturation within the ovary, at this stage, the research findings have only been made in mice.

She also points out that the drug itself can have harmful side-effects, and more research is needed to find other, safer ways of activating the protein and says weight loss is a more effective way to restore fertility.

Ms Minge says her findings emphasise the importance of a healthy lifestyle for women who want to conceive children naturally.

Cadence Minge is one of 16 young scientists presenting their research to the public for the first time thanks to Fresh Science, a national program sponsored by the Federal and Victorian Governments.

The program identifies new and interesting research being done by early-career scientists around the country.