P–633 lifestyle intervention prior to IVF does not improve embryo utilization rate and cumulative live birth rate in women with obesity
Authors: Wang Z , Groen H , Va. Zomeren1 K C , Cantineau A E P , Va. Oers A , Va. Montfoort A P A , Kuchenbecker W K H , Pelinck M J , Broekmans F J , Klijn N F , Kaaijk E M , Mol B W J , Hoek A , Echten-Arends J Va 
Published: August 2021

Abstract

Study question
Does lifestyle intervention prior to in vitro fertilization (IVF) improve embryo utilization rate (EUR) and cumulative live birth rate (CLBR) in women with obesity?

Summary answer
A six-month lifestyle intervention preceding IVF improved neither EUR, nor CLBR in women with obesity.

What is known already
A randomized controlled trial (RCT) evaluating the efficacy of a low caloric liquid formula diet (LCD) preceding IVF in women with obesity was unable to demonstrate an effect of LCD on embryo quality and live birth rate. In that study, only one fresh embryo transfer (ET) or, in case of freeze-all strategy, the first transfer with frozen-thawed embryos was reported. We hypothesized that any effect on embryo quality of a lifestyle intervention in women with obesity undergoing IVF treatment is better revealed by EUR and CLBR after transfer of fresh and frozen-thawed embryos.

Study design, size, duration
This is a nested cohort study within an RCT. The LIFEstyle study examined whether a six-month lifestyle intervention prior to assisted reproductive technology (ART) in women with obesity improved live birth rate, compared to prompt ART within 24 months after randomization. In the original study, 577 women with obesity and infertility were assigned to a lifestyle intervention followed by ART (N = 290) or to prompt ART (N = 287) between 2009 and 2012.

Participants/materials, setting, methods
The first IVF cycle with successful oocyte retrieval was included, resulting in 51 participants in the intervention group and 72 in the control group. EUR was defined as the proportion of inseminated/injected oocytes that could be transferred or cryopreserved as an embryo. Analysis was performed per cycle and per oocyte/embryo. CLBR was defined as the percentage of participants with at least one live birth from the first fresh and subsequent frozen-thawed ET(s).

Main results and the role of chance
The overall mean age was 31.64 years, and the mean BMI was 35.40 ± 3.21 kg/m2 in the intervention group, and 34.86 ± 2.86 kg/m2 in the control group (P = 0.33). The mean difference of weight change at six months between the two groups was in favor of the intervention group (mean difference in kg: –3.14, 95% CI: –5.73 – –0.56). The median (Q25; Q75) of EUR was 33.3% (12.5; 60.0) in the intervention group and 33.3% (16.7; 50.0) in the control group in the per cycle analysis (adjusted B: 2.7%, 95% CI: –8.6 – 14.0). In the per oocyte/embryo analysis, in total 280 oocytes were injected or inseminated in the intervention group, 113 were utilized (transferred or cryopreserved embryos, EUR = 40.4%); in the control group EUR was 30.8% (142/461). The lifestyle intervention did not significantly improve EUR (adjusted OR: 1.36, 95% CI: 0.94 – 1.98) in the per oocyte/embryo analysis taking into account the interdependency of the oocytes per participant. CLBR was not significantly different between the intervention group and the control group after adjusting for type of infertility (male factor and unexplained) and smoking (27.5% vs 22.2%, adjusted OR: 1.03, 95% CI: 0.43 – 2.47).

Limitations, reasons for caution
This study is a nested cohort study within an RCT, and no power calculation was performed. The randomization was not stratified for indicated treatment. The limited absolute weight loss and the short duration of the lifestyle intervention might be insufficient to affect EUR and CLBR.
Wider implications of the findings: Our data do not support the hypothesis of a beneficial effect of lifestyle intervention on embryo quality and CLBR after IVF in women with obesity.

Trial registration number
NTR 1530