The combined effect of BMI and age on ART outcomes.

Autores de IIS La Fe

• José Bellver Pradas

  Autor

• 

  Nicolás Garrido Puchalt

  Autor

Participantes ajenos a IIS La Fe

• Rafael F
• Rodrigues MD
• Canelas-Pais M
• Garcia-Velasco JA
• Soares SR
• Santos-Ribeiro S

Grupos

• Biología Reproductiva y Bioingeniería en Reproducción Humana

• Endocrinología Reproductiva e Infertilidad

Abstract

STUDY QUESTION: For a woman with infertility and overweight/obesity, can infertility treatment be postponed to first promote weight loss? SUMMARY ANSWER: Advice regarding a delay in IVF treatment to optimize female weight should consider female age, particularly in women over 38years for whom only substantial weight loss in a short period of time (3 months) seems to provide any benefit. WHAT IS KNOWN ALREADY: Body weight excess and advanced age are both common findings in infertile patients, creating the dilemma of whether to promote weight loss first or proceed to fertility treatment immediately. Despite their known impact on fertility, studies assessing the combined effect of female age and BMI on cumulative live birth rates (CLBRs) are still scarce and conflicting. STUDY DESIGN, SIZE, DURATION: We performed a multicentre retrospective cohort study including 14 213 patients undergoing their first IVF/ICSI cycle with autologous oocytes and subsequent embryo transfers, between January 2013 and February 2018 in 18 centres of a multinational private fertility clinic. BMI was subdivided into the following subgroups: underweight (<18.5kg/m2), normal weight (18.5-24.9kg/m2), overweight (25.0-29.9kg/m2), and obesity (=30.0kg/m2). PARTICIPANTS/MATERIALS, SETTING, METHODS: The primary outcome was CLBR. The secondary outcome was time to pregnancy. To assess the influence of female age and BMI on CLBR, two multivariable regression models were developed with BMI being added in the models as either an ordinal categorical variable (Model 1) or a continuous variable (Model 2) using the best-fitting fractional polynomials. CLBR was estimated over 1-year periods (Model 1) and shorter timeframes of 3months (Model 2). We then compared the predicted CLBRs according to BMI and age. MAIN RESULTS AND THE ROLE OF CHANCE: When compared to normal weight, CLBRs were lower in women who were overweight (adjusted odds ratio (aOR) 0.86, 95% CI 0.77-0.96) and obese (aOR 0.74, 95% CI 0.62-0.87). A reduction of BMI within 1year, from obesity to overweight or overweight to normal weight would be potentially beneficial up to 35years old, while only a substantial reduction (i.e. from obesity to normal BMI) would be potentially beneficial in women aged 36-38years. Above 38years of age, even considerable weight loss did not compensate for the effect of age over a 1-year span but may be beneficial in shorter time frames. In a timeframe of 3months, there is a potential benefit in CLBR if there is a loss of 1kg/m2 in BMI for women up to 33.25years and 2kg/m2 in women aged 33.50-35.50years. Older women would require more challenging weight loss to achieve clinical benefit, specifically 3kg/m2 in women aged 35.75-37.25years old, 4kg/m2 in women aged 37.50-39.00years old, and 5kg/m2 or more in women over 39.25years old. LIMITATIONS, REASONS FOR CAUTION: This study is limited by its retrospective design and lower number of women in the extreme BMI categories. The actual effect of individual weight loss on patient outcomes was also not evaluated, as this was a retrospective interpatient comparison to estimate the combined effect of weight loss and ageing in a fixed period on CLBR. WIDER IMPLICATIONS OF THE FINDINGS: Our findings suggest that there is potential benefit in weight loss strategies within 1year prior to ART, particularly in women under 35years with BMI =25kg/m2. For those over 35years of age, weight loss should be considerable or occur in a shorter timeframe to avoid the negative effect of advancing female age on CLBR. A tailored approach for weight loss, according to age, might be the best course of action. STUDY FUNDING/COMPETING INTEREST(S): No specific funding was obtained for this study. All authors have no conflicts to declare. TRIAL REGISTRATION NUMBER: N/A.

© The Author(s) 2023. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Keywords

• infertility; obesity; age; ART; cumulative live birth rate; time-to-pregnancy; weight loss; clinical decision support systems