If you’ve been told to lose weight before you can have IVF, you’re not alone. NHS funding usually requires a BMI under 30, and many clinics won’t treat above 35. The reasons given are usually two: that a higher BMI means poorer-quality eggs, and that egg collection is riskier. We looked at both.
Question 1: does BMI change egg quality?
Our lab assessed 1,031 mature eggs from 175 patients using an AI tool (CHLOE-OQ, by Fairtility) that scores each egg’s quality from its image. Using the same tool for every egg removes the biggest problem with earlier studies, where different embryologists graded eggs differently.
We grouped patients by BMI: under 25, 25 to 29.9, 30 to 39.9, and 40 or over. The average egg-quality scores were almost identical:
| BMI group | Average egg-quality score |
|---|---|
| Under 25 | 7.36 |
| 25–29.9 | 7.55 |
| 30–39.9 | 7.40 |
| 40 and over | 7.31 |
BMI explained less than 1% of the differences in egg quality. Other things, such as how the ovaries respond to stimulation, genetics and lab conditions, matter far more.
Question 2: is egg collection safe with a higher BMI?
Our nurses run a dedicated pathway for patients with a BMI of 30 or more: a pre-assessment call, a sleep-apnoea screen, positioning that keeps the airway open, oxygen on standby, specialist equipment and a structured recovery. Over a year, 56 patients with a BMI of 30 or more had egg collection on this pathway:
- Every egg collection was completed.
- No one needed a general anaesthetic or an unplanned hospital stay.
- A short dip in oxygen levels happened in 4 patients (7%), and most settled with simple airway support.
- Typical recovery took 25 minutes.
- Results were the same for patients with a BMI over 40.
What this means for you
- A BMI cut-off isn’t a good measure of whether IVF is right for you. Your overall health, your ovarian reserve and a proper safety plan matter more.
- At Avenues there’s no BMI cut-off for IVF. Fair IVF+ is £4,749 for a BMI over 35, with ICSI and medication included.
- Weight and metabolic health can still matter for pregnancy, so your doctor will talk you through what’s right for you, without making it a barrier to starting.
Your first step
Our High BMI Fertility MOT includes a scan, metabolic blood tests and a consultation with one of our doctors, in London or Cambridge: £949 for couples (female and male) or £799 for women on their own. Or book a free 15-minute call to talk it through first.
Based on our research abstracts “AI analysis shows no meaningful impact of BMI on oocyte quality” and “Beyond the cut-off: nurse-led safety outcomes” (Avenues). Larger studies are needed to confirm these findings.