The reproductive journey of women with obesity undergoing assisted reproductive technology: an analysis of 48,595 in vitro fertilization cycles in 31,829 women

Autores de IIS La Fe

• José Bellver Pradas

  Autor

• Antonio Pellicer Martínez

  Autor

• 

  Nicolás Garrido Puchalt

  Autor

Grupos

• Biología Reproductiva y Bioingeniería en Reproducción Humana

• Endocrinología Reproductiva e Infertilidad

• Medicina Fetal y Reproductiva

Abstract

Objective: To study cumulative live birth rates in in vitro fertilization per oocyte used, per embryo transferred, and per embryo transfer, according to female body mass index in a cohort in which all the ovarian stimulation cycles were performed until a live born was achieved or drop out were considered. Subjects: We included 31,829 women undergoing in vitro fertilization and using autologous oocytes and partner sperm, with known body mass index and known outcome. In total, in the cohort, there were 48,595 ovarian stimulation cycles with oocyte pick-up and 35,430 embryo transfers, 8,968 of them fresh, and 26,462 frozen, between January 1, 2017, and October 1, 2023, in 15 Spanish Main Outcome Measures: Cumulative live birth rates according to female body mass index until first live birth or drop out were recorded, using the normal weight group as the reference. Results: The numbers of oocytes inseminated until the first live born was achieved or drop out was recorded were similar in underweight and normal weight women, but were significantly higher in women who were overweight and even more so in women with obesity, as shown by the respective unadjusted hazard ratios of 0.94 95% confidence interval (CI) (0.90-0.99) and 0.85 95% CI (0.780.91), and of 0.94 95% CI (0.90-0.99) and 0.84 95%CI (0.78-0.91), when adjusted for female and male age. The numbers of embryos transferred were also higher in overweight and even more pronounced in women with obesity, with respect hazard ratios of 0.91 95% CI (0.87-0.96) and 0.85 95% CI (0.79-0.92) in the univariant analysis, and 0.89 95% CI (0.84-0.93) and 0.76 95% CI (0.70-0.82) after adjustment. The number of embryo transfers (with one or two embryos transferred) was again higher in both women who were overweight and obese, with respective hazard ratios of 0.94 95% CI (0.89-0.98) and 0.81 95% CI (0.75-0.87) in the univariant analysis, and 0.93 95% CI (0.88-0.98) and 0.78 95% CI (0.72-0.84) after adjustment. Conclusion: The higher the female body mass index, the higher the number of oocytes, embryos, and embryo transfers needed to achieve a live born. (Fertil Steril (R) 2025;124:1191-1200. (c) 2025 by American Society for Reproductive Medicine.) El resumen est & aacute; disponible en Espa & ntilde;ol al final del art & iacute;culo.

Copyright © 2025 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Keywords

• Obesity; IVF; cumulative live birth rates; clinical yield; reproductive journey