High BMI? What IVF Patients Need to Know

03 Apr High BMI? What IVF Patients Need to Know

Is your BMI too high for IVF treatment? Many clinics will treat patients with a BMI of up to 35. But are your chances of success really reduced if you’re overweight? Let’s look at the research.

Obesity is on the rise. It’s well-known that being overweight affects fertility and pregnancy outcomes. When it comes to IVF, findings have become clearer in the last 10 years (when IVF has come into its own). A 2019 study looked at data from 21 previous studies. It found that live birth rates were significantly lower for women with a BMI of 30 or more. (A normal BMI is 18.5 to 24.9.) PCOS patients, often with high BMIs, had poorer prognoses too.

As far back as 2010, the general problems of overweight IVF patients were being highlighted. Obese women (i.e. with a BMI of 30 or more) often require higher doses of gonadotrophins (always a risk). They may respond less well to ovarian stimulation and produce fewer eggs. Embryos can be lower quality. Fertilisation rates are lower. And miscarriages sadly happen more often.

Away from that study, research shows that being overweight is bad for male fertility too (this is often overlooked). As is being underweight: women with a subnormal BMI can have fertility, ovulatory and hormonal problems, all of which affect lower IVF success rates.

Many other studies point to the negatives of high BMI and IVF outcomes. Not all are equally gloomy. A 2017 study couldn’t find much evidence that egg quality and endometrial receptivity were issues for overweight patients. And a study two years earlier found that high-BMI IVF patients needed more FSH medication and longer stimulation durations, but that clinical-pregnancy rates were largely unaffected.

Treating overweight patients is a challenge for IVF clinics. General anaesthesia is a risk: IVF patients with a BMI of 35 or more are routinely refused treatment. But clinics have also learned to manage overweight IVF patients better. Improved counselling and patient communication can prepare patients with poorer prognoses.

Safer protocols for PCOS patients are now the norm. More creativity in FSH medication regimes can counter, to some extent, negative aspects of high-BMI patients. And add-on treatments, such as blood thinners and low-dose steroids, may improve outcomes for overweight IVF patients too.

But there’s no getting way from it. The best thing a prospective IVF patient can do is to get their BMI into the normal range. Or close to it. So if you’re nervous, set a realistic target. A BMI of 30 is better than 32, and 28 is better than 30. Don’t feel stigmatised. There’s plenty of research that criticises overtly strict judgements of high-BMI fertility patients. Those in the firing line include NHS providers who point-blank refuse treatment to patients with a BMI of over 30, or less. That kind of unfairness gives medical science a bad name.

We’ve seen successful IVF pregnancies with BMIs above 30. So having a ‘healthy’ BMI is only one piece of the jigsaw. A balanced diet, a positive outlook and reasonable expectations may be just as important.