Obesity (Silver Spring). 2013 Aug;21(8):1608-12.

Male adiposity impairs clinical pregnancy rate by in vitro fertilization without affecting day 3 embryo quality.

Merhi ZO, Keltz J, Zapantis A, Younger J, Berger D, Lieman HJ, Jindal SK, Polotsky AJ.

Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, University of Vermont College of Medicine, Burlington, VT, USA.



OBJECTIVE: Male adiposity is detrimental for achieving clinical pregnancy rate (CPR) following assisted reproductive technologies (ART). The hypothesis that the association of male adiposity with decreased success following ART is mediated by worse embryo quality was tested.

DESIGN AND METHODS: Retrospective study including 344 infertile couples undergoing in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) cycles was performed. Cycle determinants included number of oocytes retrieved, zygote PN-score, total number of embryos available on day 3, number of embryos transferred, composite day 3 grade for transferred embryos, composite day 3 grade per cycle, and CPR.

RESULTS: Couples with male body mass index (BMI) over 25 kg m(-2) (overweight and obese) exhibited significantly lower CPR compared to their normal weight counterparts (46.7% vs. 32.0% respectively, P = 0.02). No significant difference was observed for any embryo quality metrics when analyzed by male BMI: mean zygote PN-scores, mean composite day 3 grades for transferred embryos or composite day 3 grades per cycle. In a multivariable logistic regression analysis adjusting for female age, female BMI, number of embryos transferred and sperm concentration, male BMI over 25 kg m(-2) was associated with a lower chance for CPR after IVF (OR = 0.17 [95% CI: 0.04-0.65]; P = 0.01) but not after ICSI cycles (OR = 0.88 [95% CI: 0.41-1.88]; P = 0.75). In this cohort, male adiposity was associated with decreased CPR following IVF but embryo quality was not affected.

CONCLUSIONS: Embryo grading based on conventional morphologic criteria does not explain the poorer clinical pregnancy outcomes seen in couples with overweight or obese male partner.

Copyright © 2013 The Obesity Society.

PMID: 23754329



How do you solve the puzzle of why obesity reduces the chances of conception?

By eliminating one possibility at a time.

In the newest attempt, we have looked into the low quality of embryos possibly being the connection between male obesity and decreased in vitro fertilization (IVF) success rates. We evaluated various possibilities that may explain this connection, and found that embryo quality is not the reason.  That means we don’t have to follow that false prospect and we can move on to study other possible connections. And at the same time our study shows that male obesity affects IVF success. Overweight men have a harder time conceiving and that’s one more important reason to counteract effects of obesity.

Recently published in Obesity, the research study involved 344 infertile couples undergoing fertility treatment. We found that couples with obese or overweight men were significantly less likely to achieve clinical pregnancy in IVF as compared to couples in which the male was not overweight or obese (32% and 46.7% respectively).   The smaller puzzle remains: how does male obesity affect IVF outcomes, and by extension how does it affect fertility?  Our research (1) and research of others’ show (2) that male obesity does not appear to impact success of intra-cytoplasmic sperm injection (ICSI) cycles but decreases clinical pregnancy after conventional IVF.  This trend is seen regardless of semen parameters and embryo quality assessment.

It is possible that current means of evaluating sperm and embryos are not adequate and need to be researched for further clues. Additionally, ICSI may somehow overcome the harmful impact of male obesity on reproductive potential.  The significance of this health hazard is clear: if we can find the molecular links of how adiposity affects fertility, it could clarify how obesity acts to cause other health problems.

Clinical Pregnancy by Male BMIAlex J. Polotsky-1Overweight men: clinical pregnancy after ART is decreased
Keltz J, Zapantis A, Jindal SK, Lieman HJ, Santoro N, Polotsky AJ.
J Assist Reprod Genet. 2010 ;27(9-10):539-44


  1. Overweight men: clinical pregnancy after ART is decreased Keltz J, Zapantis A, Jindal SK, Lieman HJ, Santoro N, Polotsky AJ.J Assist Reprod Genet. 2010 ;27(9-10):539-44
  2. The influence of female and male body mass index on live births after assisted reproductive technology treatment: a nationwide register-based cohort study. Petersen GL, Schmidt L, Pinborg A, Kamper-Jørgensen M. Fertil Steril. 2013;99:1654-62.
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