Obesity: A Doorway to a Molecular Path Leading to Infertility

Abstract

The dramatic rise in obesity has recently made it a global health issue. About 1.9 billion were overweight, and 650 million global populations were obese in 2016. Obese women suffer longer conception time, lowered fertility rates, and greater rates of miscarriage. Obesity alters hormones such as adiponectin and leptin, affecting all levels within the hypothalamic-pituitary-gonadal axis. Advanced glycation end products (AGEs) and monocyte chemotactic protein-1 (MCP-1) are inflammatory cytokines that may play an important role in the pathophysiology of ovarian dysfunction in obesity. In obese males, there are altered sperm parameters, reduced testosterone, increased estradiol, hypogonadism, and epigenetic modifications transmitted to offspring. The focus of this article is on the possible adverse effects on reproductive health resulting from obesity and sheds light on different molecular pathways linking obesity with infertility in both female and male subjects. Electronic databases such as Google Scholar, Embase, Science Direct, PubMed, and Google Search Engine were utilized to find obesity and infertility-related papers. The search strategy is detailed in the method section. Even though multiple research work has shown that obesity impacts fertility in both male and female negatively, it is significant to perform extensive research on the molecular mechanisms that link obesity to infertility. This is to find therapeutics that may be developed aiming at these mechanisms to manage and prevent the negative effects of obesity on the reproductive system.

The Molecular Basis of Male Infertility in Obesity: A Literature Review

“…The production of adiponectin by adipose tissue increases during starvation and is inversely related in obese individuals to visceral adiposity and BMI [ 1 , 37 , 38 ]. Furthermore, adiponectin increases insulin sensitivity.…”

“…Decreases in adiponectin levels result in insulin resistance and metabolic syndrome. Adiponectin levels have been found to be low in obese females [ 1 ].…”

“…Overweight and obesity are terms used to describe an abnormal and excessive build-up of body fat that may have a detrimental effect on health [ 1 ]. Body mass index (BMI) is a measure of body weight per height that is widely used to classify adults as overweight or obese.…”

Obesity inflicted reproductive complications and infertility in men

“…An unhealthy eating habit and a sedentary lifestyle contributes to obesity significantly and when there is a rise in 10% of sedentary time, the waist circumference increase by 3.1cm 65,74 . Regular exercise helps combat obesity as it promotes general well-beingand improvement of insulin sensitivity 75 . High fat diet has been noted to deteriorate sperm cells' physical and molecular structure 68,76 .…”

Maternal prepregnancy body mass index, gestational weight gain, and allergic diseases in children: A systematic review and meta‐analysis

“…The number of general population and pregnant women affected by overweight and obesity has risen rapidly. According to the World Health Organization (WHO), in 2021, 13% of adults worldwide suffered from being overweight (40% of them were female), and 13% of adults globally affected by obesity (15% of them were female) 1 . Likewise, the number of women of reproductive age affected by overweight and obesity has increased dramatically, with approximately half of US women of reproductive age now being considered to be affected by overweight or obesity 2,3 .…”