O-072 Lack of meaningful impact of male body mass index (BMI) on reproductive outcomes measured by cumulative live birth rates (CLBR) in 80830 IVF-ICSI treatments
Authors: Mossetti L , Hervás Herrero I , Gil Julia M , Navarro Gómez-Lechón A , Pacheco Rendón R M , Rivera Egea R , Garrido Puchalt N 
Published: June 2023

Study question

Does men’s BMI influence the reproductive success measured as CLBR per embryo transfer(ET), embryos replaced(EmbR) and oocytes utilized, if female BMI is controlled?

Summary answer

Male’s BMI do not affect reproductive outcomes, although obese males seem to need slightly more ET to reach the first live birth.

What is known already

Obesity is a systemic, chronic and multifactorial disease present worldwide, involving all ages, ethnicities and social classes, and associated with hormonal alterations that may lead to a decrease in seminal quality and reproductive outcomes. The exact mechanisms involved, between excess body fat and reproductive disturbances, if any, are complex and unknown. This leads us to investigate the effect of BMI on reproductive outcomes to carry out a better counseling of couples who go to a clinic for assisted reproduction treatment. The recent improvement of measuring reproductive success by cumulative rates has never been applied to many risk factors, as obesity.

Study design, size, duration

This retrospective observational multicentric study has evaluated the results from 80830 IVF-ICSI treatments, 298422 oocytes and 215357 embryos transferred performed in Spanish IVIRMA fertility clinics between January 2008 and December 2020 by couples using their own sperm sample and oocytes.

Participants/materials, setting, methods

Couples attending IVI clinics. Male BMI was categorized in: underweight (&lt;18.5 kg/m2) (U), normal weight (18.5-24.99 kg/m2) (N), overweight (25-29.99 kg/m2) (OV) and obese (≥ 30 kg/m2) (OB) patients, and CLBR were calculated using Kaplan Meier methods, by Cox regression to control women’s BMI and age, and male’s age. Reproductive success was calculated by CLBR perET, EmbR and utilized oocytes until the first LB. Data were expressed as % with corresponding 95% confidence intervals.

Main results and the role of chance

After 3 ETs, CLBR per ET, were, for groups U,N,OV and OB, respectively, 47.4%(44.3-50.3), 48.1%(47.4-48.9), 47.8%(46.2-49.4) and 47.1%(44.1-49.9), increasing after 5 ETs to 64.6(59.7-69.0), 65.1%(63.9-66.2), 62.8%,(60.2-65.3) and 59.2%(54.5-63.4).

There were statistically significant differences between Obesity and Normal weight groups (p = 0.03), hazard ratio [HR]: -0.01 on the Cox regression adjusted by female’s age and BMI, and male’s age.

Considering EmbR, after 3, CLBR were 38.8%(36.2-41.26), 35.7%(35.1-36.3), 35.2%(34.0-36.4) and 33.7%(31.5-35.9), and after 6 EmbR, 62.7%(58.5-66.5), 59.8%, (58.9-60.7), 59.8%(57.7-61.8) and 58.0%(54.1-61.5), for U, N, OV, and OB respectively, with no significant differences among groups, also confirmed by the comparable results adjusted Cox regression.

Concerning CLBR per oocyte used, with 8 oocytes, results were 38.3%(35.2-41.3), 34.7%(33.9-35.4), 32.0%(30.6-33.4) and 29.9%(27.4-32.3), and after 12 oocytes used, 54.0%(50.6-57.3), 53.5%(52.7-54.3), 49.9%(48.3-51.5) and 46.8%(43.9-49.6), for the above mentioned ordered IMC groups.

Considering 16 oocytes used, results on U, N, OV and OB males were also comparable: 69.6%(65.9-72.8), 66.7%(65.9-67.5), 62.6%(60.8-64.3) and 62.1%(58.8-65.2), respectively, also confirmed by Cox regression adjusted estimates.

Limitations, reasons for caution

The retrospective nature of this study leads to biases derived from the clinical practice and the presence of missing/incomplete or imprecise data, together with the possibility of not having controlled by all possible confounding factors.

Wider implications of the findings

Different male’s BMI, when controlled by main confounders, show comparable results in the number of oocytes needed, EmbR to get the first child, and, although we confirmed a minor influence on ET needed, the message is that male’s weight seems not affecting reproductive outcomes in IVF/ICSI treatments.

Trial registration number

not applicable