Does losing weight between IVF cycles lead to more eggs or better fertilization?

What did this research set out to answer? 

Researchers wanted to understand whether gaining or losing weight between in vitro fertilization (IVF) cycles affects how the ovaries respond to treatment and what happens in the lab after eggs are retrieved. 

They looked specifically at whether weight changes were associated with differences in: 
   •    The number and maturity of eggs retrieved 
   •    Fertilization rates 
   •    How many fertilized eggs developed into usable blastocysts

What did the researchers do?

Researchers reviewed past IVF treatment data from 961 patients who had at least two IVF cycles and experienced a change in weight within one year of their initial IVF cycle. 

Instead of comparing different groups of patients, they compared each patient's IVF cycles before and after their weight changed. Of the 961 patients, 354 lost weight and 607 gained weight between IVF cycles. 

The researchers considered factors that could also affect IVF results, including age, initial weight, ovarian reserve, and fertility medication dose. 

What did the research find? 

Weight loss between IVF cycles was not associated with significant improvements in the IVF outcomes researchers studied: 
   •    Eggs retrieved 
   •    Mature eggs 
   •    Fertilization rates 
   •    Blastocyst development 

Researchers found small positive associations between weight gain and the number of eggs retrieved, mature eggs and fertilization, but the overall effects were small. 

The researchers concluded that neither weight loss nor weight gain was associated with clinically important changes in IVF cycle outcomes following ovarian stimulation. 

What does this mean for patients?

If you’re considering delaying IVF specifically to lose weight in hopes of retrieving more eggs or improving fertilization, this study did not find evidence that weight loss improved those outcomes. 

Weight can still play an important role in overall health and pregnancy health. This study did not evaluate pregnancy or live birth rates, and the authors point to separate research suggesting weight loss may reduce certain pregnancy-related risks. 

Your care team can help you weigh these factors and decide what makes sense for your health, age and treatment goals. 

Fouks, Y., Vaughan, D. A., Neuhausser, W., Cohen, Y., Penzias, A. S., & Sakkas, D. (2024). Intra-patient analysis of individual weight gain or loss between IVF cycles: cycle now and transfer later. Human Reproduction, 39(1), 93–101. https://doi.org/10.1093/humrep/dead244