Obesity and Reproductive Disorders

Obesity, which results from a combination of genetic and environmental factors, is an increasingly prevalent condition in Western society that heightens the risk for reproductive disorders. Lifestyle modifications, including dietary changes and exercise, can go a long way toward restoring ovulation in this patient population.

Overeating and lack of exercise, as well as a more sedentary lifestyle overall, are associated with weight problems in a growing proportion of the population. In 1997, an estimated 33% of US adults were obese; the highest rates were found among women (34%), Hispanics (47%), and African-Americans (49%).

Up to 55% of US adults are considered overweight (i.e., above their healthy weight range). Excess weight can be classified more precisely using body mass index (BMI): A BMI of 27 to 29.9 kg per m2 is designated as overweight and a BMI of 30 kg per m2 or higher is termed obese.

Obesity is associated with a host of medical conditions, including diabetes mellitus, osteoarthritis, cardiovascular disease, sleep apnea, breast and uterine cancer, pregnancy complications, and reproductive disorders. Total weight, although important, is not the sole factor in these problems, however; fat distribution is also key. This can be assessed using the waist/hip ratio or, simply, waist circumference.

A disproportionate number of women who seek treatment at infertility centers have a high BMI. For example, among more than 5000 infertile female patients seen at the Reproductive Medicine Unit at the University of Adelaide, Australia, 40% had a BMI exceeding 25 kg per m2 (borderline or overweight), and 17% had a BMI exceeding 30 kg per m2 (obese). Thus, excess weight appears to have a major impact on reproductive performance, and obesity can compromise reproductive performance in a variety of ways. It should be noted that although many obese women are fertile and have children, the overall prevalence of reproductive disorders increases significantly once women reach the overweight and obese ranges. The large number of very overweight, fertile women should not lead practitioners to assume that weight disorders have little impact on reproduction.

PCOS
Five percent to 10% of all women of reproductive age have polycystic ovary syndrome (PCOS). Clinical features of this disorder are listed in Table 2. Although some controversy exists regarding the definition of PCOS, the presence of menstrual abnormalities, hirsutism, obesity, and infertility makes the diagnosis unequivocal. Not all obese women have PCOS, nor are all women with PCOS obese, but the two conditions are closely related.

Initial investigations in patients with suspected PCOS should include a clinical examination and basic laboratory studies. The recommended work-up for these patients, as well as for any obese women with reproductive difficulties, appears in Table 3. It is particularly important to exclude glucose intolerance, through either a fasting blood glucose test or an oral glucose tolerance test. Some evidence has suggested that fasting glucose is not entirely reliable in patients with PCOS; instead, fasting and stimulated serum insulin values may be useful.