September 27, 2017
The first comparison by advanced computer-aided semen analysis (CASA) shows that sperm from obese infertile men is of poor quality, quantity, and morphology compared with that of infertile but normal-weight men.
Results from a retrospective cohort study of 1285 infertile men show that a body mass index (BMI) of 30 or higher was associated with lower semen volume (P = .04), sperm count (P = .002), concentration (P = .01), progressive motility (P = .001), and total motility (P = .002) compared with men with a BMI in the normal range, according to Gottumukkala Achyuta Ramaraju, MBBS, of the Center for Assisted Reproduction, Krishna IVF Clinic, Visakhapatnam, India, and colleagues.
"This is the first report of abnormal sperm parameters in obese men based on CASA," the study authors say in their report, published online September 19 in Andrologia.
"The health and reproductive performance of spermatozoa in obese men are more likely to be compromised both qualitatively and quantitatively," noted Dr Ramaraju in a statement. "Clinicians may need to factor in paternal obesity prior to assisted reproduction."
Obese Men Should Lose Weight Prior to Infertility Treatment
The mean age of the study cohort, made up of men presenting to an infertility clinic for treatment between January and December 2016, was 35 years. A total of 201 (16%) were obese. The researchers categorized spermatozoa as progressive, nonprogressive, and immotile using 2010 guidelines from the World Health Organization (WHO).
CASA makes it possible to assess more sperm parameters with greater overall reliability compared with conventional microscopic methods, the researchers say.
In the study, obesity was also associated with lower average curve velocity (P = .001) of sperm, average path velocity (P = .006), and with morphological changes such as a higher percentage of head defects (P = .02), thin heads (P = .007), and pyriform heads (P = .02) than nonobesity.
The study also demonstrates a link between obesity and categorical outcomes of male infertility, including oligospermia, defined as < 15 million/mL spermatozoa (odds ratio [OR], 1.67, P = .007) and asthenospermia, defined as < 40% motile spermatozoa (OR, 1.82 P = .005).
Although a link between obesity and sperm abnormalities has been suspected for some time, previous study results have been mixed and inconclusive, Dr Ramaraju and colleagues add.
Some studies reported negative associations between obesity and sperm count, concentration, motility, and number of normal morphological forms, while others found no association between obesity and sperm parameters.
"Previous null findings between obesity and sperm-quality measures may be due to failure to account for potential confounders," the investigators suggest, adding, however, that additional research is required to further validate their observations.
"The effect of obesity on sperm quality has been a topic of great interest, and there is sufficient literature on potential mechanisms through which obesity impairs sperm function. Yet there is a lack of consensus on individual sperm parameters influenced by obesity."
And prior studies into the link between obesity and fertility have shown that paternal obesity at conception can have a negative impact on the health of the embryo as well as deleterious consequences for implantation, pregnancy, and live birth rates.
More recently, findings from epigenetic research show that male obesity can affect the fertility of future children, the study authors point out.
And after weight loss — whether through diet and exercise or bariatric surgery — normalized ratios of testosterone and estrogen and increased levels of plasma sex hormone-binding globulin (SHBG) have been reported, the investigators note.
Normalized sperm microRNA profiles and metabolic syndrome have also been observed in the children of obese fathers who lost weight, while improvements in sperm concentration and motility were observed following weight loss and supplementation with vitamin C, they add.
The study authors report no relevant financial relationships.