BMI values ≤28 kg/m2 in egg donors do not affect the success of assisted reproduction
A team of research scientists led by the Reproductive Medicine Unit of Dexeus Mujer conducted an extensive retrospective study on a total of 2,722 consecutive ART cycles carried out between January 2007 and December 2014, the objective of which was to determine whether a higher body mass index (BMI) in egg donors can affect the outcome of assisted reproduction, particularly in terms of pregnancy and live birth rates.
In general, both overweight and obesity are associated with an increased risk of miscarriage and complications during pregnancy, as well as decreased ART success rates. While the reasons remain unclear, some theories have been postulated. On the one hand, obesity is thought to affect uterine receptivity due to its negative effects on endometrial tissue, and on the other hand, these problems could be related to a disturbance in ovarian metabolism, directly affecting the oocytes.
Taking this into account, the study team reviewed a total of 2,722 egg donation cycles performed by Dexeus Mujer in order to determine whether a high or low donor BMI could influence the outcomes. To this end, donors were classified into four categories: Q1- BMI ≤19.9 kg/m2 (16.20-19.90), Q2- 19.91-21.5 kg/m2, Q3- 21.60-23.50 kg/m2, Q4- ≥23.51 kg/m2. Donor BMI averaged 21.8 kg/m2, and donor age 26.5±4.5 years.
The total number of donors was 2,208, but the eggs of only 514 of them were shared. A total of 1,347 pregnancies were achieved after fresh and deferred embryo transfers. Of those 1,347 pregnancies 255 ended in miscarriage, and there were 928 live births after fresh embryo transfer and 250 after frozen embryo transfer.
The BMI of the patients who underwent egg donation treatment averaged 22.92±3.83 kg/m2, and donor age 42.44±4.28 years. Of these women, 316 had a BMI between 25 and 30 kg/m2, and 160 had a BMI above 30 kg/m2. In order to eliminate the potential impact of recipient BMI on the results, these were adjusted for this variable.
After completing the study, the authors concluded that a donor BMI of ≤ 28 kg/m2 had no negative impact and yielded no significant differences in the outcomes of egg donation cycles, although they admitted not to know whether a BMI beyond this value could have a detrimental effect, since the screening criteria for donation programs set a limit for the BMI of donor candidates -of 28 kg/m2 in the case of Dexeus Mujer- precisely because of the proven adverse effects of obesity on ART. Nevertheless, in order to minimise these potential adverse effects, the authors stress that it is best to maintain current criteria when screening donors, in order to avoid the potential negative effects of high BMI on egg donation treatment outcomes. The findings of this study were published in Reproductive Biomedicine Online.
Reproductive outcomes in recipients are not associated with oocyte donor body mass index up to 28 kg/m2: a cohort study of 2722 cycles
Martínez F, Kava-Braverman A, Clúa E, Rodríguez I, Gaggiotti Marre S, Coroleu B, Barri PN.
Reprod Biomed Online. 2017 Aug 15. pii: S1472-6483(17)30376-0.