Obesity and reproductive function

Abstract

SYNOPSISObesity is associated with multiple adverse reproductive outcomes, but the mechanisms involved are largely unknown. Public health scientists studying obesity and its effects on health outcomes have referred to obesity as a "complex system", defined as a system of heterogeneous parts interacting in nonlinear ways to influence the behavior of the parts as a whole 1,22 . By this definition, human reproduction is also a complex system which may explain some of the difficulty in identifying the mechanisms linking obesity and adverse reproductive function. Despite the difficulties, research on obesity and reproduction is important as there is an epidemic of obesity among reproductive age women with associated consequences for future generations. In this review we discuss the adverse reproductive outcomes associated with obesity and data from translational studies of the mechanisms involved. We conclude with a brief discussion of public health policy as it relates to the treatment of infertility in obese women. Keywords fertility; obesity; reproduction; public health MEASURING OBESITY AND REPRODUCTIVE RISKDisentangling the individual components of obesity associated with poor health outcomes is difficult. Body mass index (BMI) or overall body size adjusted for height, is obviously, the most accessible measure of obesity as the tools for measuring BMI are readily available. On the other hand, adiposity (regional or total body fat), adipokine production, and lifestyle components may also contribute individually or together to overall obesity-related health risk. The bulk of the work relating obesity to health risks has focused on chronic diseases, however, we are learning more about components of obesity that relate to reproductive risk.

The impact of adipose tissue-derived factors on the hypothalamic-pituitary-gonadal (HPG) axis

“…These findings suggest that both adipokines and inflammatory factors exert an impact on the HPG axis and on fertility. In humans, the data are fairly consistent regarding the finding that obesity, via metabolic inflammation, results in reduced fertility in women 11 and men. 12 Inflammationinduced leptin resistance has been proposed as being a potential mechanism 13 linking obesity with HPG axis defects and subfertility.…”

Demographic, lifestyle, and other factors in relation to antimüllerian hormone levels in mostly late premenopausal women

“…Our non-significant association between BMI and AMH is consistent with the results from most studies of healthy women. While obese premenopausal women are more likely to experience anovulation than normal weight women (78), which may increase the number of small antral follicles that secrete AMH (79), obesity also increases adipokines and/or inflammatory markers in the ovaries, thereby potentially impairing follicle function which could lead to decreased AMH(76, 77). These opposite effects could explain the lack of clear association between AMH and BMI.…”

Bariatric and metabolic surgery: a shift in eligibility and success criteria

“…In addition, obesity is a known risk factor for infertility in women. 133 Nearly 50% of patients undergoing bariatric surgery are women of reproductive age, with fertility in obese women improving after surgical interventions. 134,135 Thus, addressing the reproductive health of women should also be considered as an indication for bariatric surgery in patients in whom infertility might be related to increased adiposity and its subsequent hyper insulinaemia, hyperleptinaemia and resultant hyperandrogenism.…”