Is there a BMI limit for IVF? The rules in the UK, France and Greece

The issue of a BMI limit for IVF is a sensitive one, and it often arises after you’ve been presented with a figure: a funding threshold, a request to wait, or sometimes a refusal. Your weight is neither a fault nor a judgement on you; it is one medical factor amongst others, such as age. Here, country by country, is what the regulations state, what is determined by the clinic, and what the studies show.

Calculating your BMI for IVF

Body Mass Index (BMI) is calculated by dividing your weight, in kilograms, by the square of your height, in metres. Example: for 70 kg and 1.65 m, the calculation is 70 ÷ (1.65 × 1.65), or 70 ÷ 2.72, which gives a BMI of approximately 25.7.

For adults, the World Health Organisation defines a BMI of 25 or above as ‘overweight’ and 30 or above as ‘obese’; the UK fertility guidelines consider a BMI below 18.5 to be low. It is an imperfect tool, which does not distinguish between muscle and fat, but it is the one used in studies and funding guidelines. The impact of weight on fertility itself is detailed in the article on weight and IVF.

BMI limits for IVF: rules by country

In the United Kingdom: a threshold for public funding

In England, IVF funded by the National Health Service (NHS) is the responsibility of local health authorities, the integrated care boards (ICBs). According to the Department of Health, most require a BMI between 19 and 30 for the woman carrying the pregnancy. Some are stricter: one requires a BMI of between 19 and 29.5, recorded in the patient’s file for at least six months; the policy of another authority, adopted in 2023, also requires a BMI of less than 30 for the partner providing the gametes.

The national NICE guidance, revised in March 2026, does not set a BMI threshold for access to IVF. It states that women with a BMI of 30 or above should be informed that they are likely to take longer to conceive, and men in the same situation should be informed that their fertility may be reduced. In the private sector, therefore, it is the clinic that sets its own rules.

In France and Greece: no statutory threshold

In France, the legal conditions for access relate to age and consent: medically assisted reproduction is permitted up to the 45th birthday of the woman who will carry the child, and egg retrieval up to the age of 43. No weight-related conditions are specified. However, the clinic’s team assesses each application and may accept, defer or reject it, depending in particular on the chances of success. I have not found any published national thresholds; practices vary from one clinic to another.

In Greece, neither the law on medically assisted reproduction nor the National Authority’s code of ethics makes any mention of BMI. The decision rests with the clinic and, in the case of egg retrieval under sedation, with the anaesthetist. This is also the position of the American Society for Reproductive Medicine (ASRM): it sees no medical or ethical reason to impose a standard threshold, and believes that each programme can set its own, depending on its ability to carry out the procedures safely and in conjunction with its anaesthesia team.

Why thresholds exist: what the studies show

A large meta-analysis published in 2019 brought together 21 studies and more than 680,000 IVF cycles. Compared with women of normal weight, the probability of a live birth was lower, in relative terms:

• by approximately 15 per cent in cases of obesity (relative risk of 0.85);
• by approximately 6 per cent in cases of overweight (0.94);
• even more so when obesity was associated with polycystic ovary syndrome (see PCOS and IVF).

The origin of the eggs, whether donated or not, did not alter this conclusion. There are two additional safety considerations, as described by the ASRM: sedation requires greater precautions, as oxygenation can be more difficult in cases of severe obesity, and ultrasound scanning of the ovaries is often more challenging. Finally, pregnancy carries greater risks, notably pre-eclampsia, gestational diabetes and caesarean section (see the risks of pregnancy following IVF).

Should you wait and lose weight before undergoing IVF?

This is the most sensitive question, and randomised trials provide a nuanced answer. In a Nordic trial published in 2017, 317 women under the age of 38, with a BMI between 30 and 35, were randomised between an intensive weight-loss programme followed by IVF and direct IVF: 29.6 per cent of births in one group, 27.5 per cent in the other – a difference that is not statistically significant. However, there were more births following a spontaneous pregnancy in the programme group.

The ASRM reaches a similar conclusion: weight-loss programmes have not improved birth rates following IVF, and taking the time to lose weight may be detrimental to older women. It adds that obesity should not, in itself, be a reason for refusal. If a clinic asks you to wait, ask them why, for how long, what support will be provided, and what this delay means given your age. What is useful during these months is preparing for IVF three months in advance.

My advice if you’re considering Greece

Send your height, weight and medical history to the clinic before booking anything, particularly if you have sleep apnoea, high blood pressure or diabetes. Ask how the sedation is administered, who assesses it, and what the plan is if the egg retrieval cannot go ahead as planned (see the egg retrieval process). A detailed answer is better than a quick ‘no problem’; further questions to ask can be found in choosing a clinic abroad. If you would like us to review your situation together, please write to me.

Frequently asked questions

Source: https://fertilitegrece.com/en/blog/ivf-bmi-limit-by-country/ — Triada Baloukoudis, IVF patient coordination in Greece. General information, not medical or legal advice. Printed on

Triada Baloukoudis
Independent IVF patient coordinator in Thessaloniki, with 24 years of experience supporting patients travelling from abroad. More · Contact · Facebook