Obesity And Infertility

Obesity can be a frustrating condition for sufferer and clinician alike!

We are all aware of the worrying cluster of health problems associated with obesity. From a fertility viewpoint, obesity is correlated with decreased fertility and suboptimal pregnancy outcomes.

The genetic component of obesity was underlined by a Danish group (Stunkard. NEJM 1986), who found the weights of adopted children correlated with the weights of their biological parents, but not of their adoptive parents. However, another European study, commenting on the role of the environment, found the prevalence of obesity to be inversely related to the level of physical activity and education and directly related to parity (number of babies).

Where there is android obesity (the “apple shape” rather than the “pear shape”), a waist circumference greater than 90cm in women (100cm in men) is predictive of abnormal metabolic function and is associated with increased cardiovascular risk. This metabolically active fat, located around the internal body organs, is also associated with hyperinsulinaemia and the increased risk of type 2 diabetes.

About 30 – 50% of woman with Polycystic Ovarian Syndrome (PCOS) have android obesity. PCOS is associated with a 5-10 fold greater risk of type 2 diabetes, with the age of onset being 30 years younger than the general population. In pregnancy there is an increased risk of PCOS patients developing gestational diabetes (type 2). The perinatal mortality and the risk of congenital malformations in type 2 diabetes now equals or has overtaken that of type 1 diabetes (Cheung.ANZJOG 2005).

On the positive side, considerable evidence shows that weight loss in PCOS can lead to the return of ovulatory cycles, decreased acne and hairiness, and improved fertility. The weight loss has to be at least 5% of body weight, but surprisingly, does not require a return to the normal range.

Management of obesity rests with the long held tenets of eating appropriately and exercising adequately. A benefi t of strenuous or prolonged exercise is an inhibition of appetite that lasts for many hours and is associated with an increase in the resting metabolic rate for 2 – 48 hours. Frustratingly, tackling lifestyle change is tough and remains a signifi cant challenge in obesity management.