Health Guide

Fertility Fitness - the impact of increased weight on fertility

Thirty seven percent of Australians are overweight or obese according to recent Australian Bureau of Statistics data and the number is rising. In addition to the association with cardiovascular disease, diabetes and some cancers, increased weight has now been shown to have an adverse effect on fertility and also increases the risk of miscarriage.

This association was first noted in studies in the 1950's but received little attention until the last decade. Most of the work to date has concentrated on fertility issues in women. As a woman's weight increases she requires higher levels of insulin to maintain a normal blood glucose level. These increased levels impact on the ovary, stopping ovulation and leading to increased male hormone levels. The result is irregular menstrual cycles and fertility problems. Women who have been diagnosed as having polycystic ovaries (PCO) are particularly at risk. Some studies have shown that even women at the higher end of the normal weight range can have their fertility affected.

Increased weight can also impact on the effectiveness of fertility treatments. As a woman's weight increases, she will require more drugs to get the desired response, and in up to 30% of cases, will still not respond well enough for treatment to occur. In addition, despite the increased stimulation, her chance of pregnancy is significantly reduced as a consequence of the effects of the increased weight.

If a pregnancy does occur the risk of miscarriage is increased, with once again women with PCO being particularly at risk.

The good news is that a small amount of weight loss can reverse these problems. An Australian study, which was a world first, has shown that a group programme of exercise and dietary advice, without an emphasis on low calories, can restore menstrual regularity and therefore ovulation and pregnancy for up to 90% of the women involved. Even women with causes of infertility unrelated to producing an egg each month (anovulation), such as tubal blockage or male sperm problems, showed a dramatic improvement in their chance of pregnancy on treatment. In addition, the risk of miscarriage was significantly improved. The women lost a maximum of seven to ten kilograms over six months so it was not necessary to get back to the normal weight range to get the beneficial effects. Even a 2-5% weight change was effective in restoring ovulation.

The study found that lifestyle changes are much easier for women to achieve if they were part of a group of women with the same fertility aims as themselves. Conversely, individual dietary advice and lifestyle management has not been shown to be particularly effective. The advantage of the group programme is that it appears that the weight loss is sustained and therefore it is likely that long-term health benefits will also result.

The programme is currently available to women who live in Sydney, Melbourne or Adelaide. Contact details can be obtained through ACCESS. (link to about Access)

Very little is known as yet about the effects of increased weight on male fertility. We do know that as a man's weight increases his testosterone levels can drop and in extreme situations there is an alteration in the semen profile. A study is now underway to explore this issue further. It is being run in association with the Gutbusters programme. Any overweight men interested in seeing the effects of weight loss on their sperm and hormonal profile can contact Wendy on (02) 9586 3214.

In summary, for women in particular, weight loss should be considered as part of the initial treatment of any woman above her 'weight for height' average, who requires fertility management, irrespective of whether it is as simple as ovulation induction or as complicated as IVF. As anyone who has tried to lose weight knows, getting the bit of your brain that wants to lose weight to connect to the bit that has to do it, is very difficult. However, making use of group dynamics, either with a specific programme associated with a fertility clinic or some other means, has been shown to be most effective in achieving the aims of weight loss, pregnancy and a healthy outcome.

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