Heavy people are often denied IVF on grounds that it won't work or that it's not cost-effective. The evidence suggests it may be something else.
Obesity can affect fertility: it can disrupt menstruation, mess up ovulation and complicate pregnancy.
But the picture is far from straightforward. Yes, anovulation is more common in obese women than in normal-weight women. But other factors matter too, such as where fat is stored: when BMI is the same, the thick-waisted are more likely to have ovulation issues. And sure, heavier women need to take more fertility drugs and that can have consequences. But when certain drugs are combined with intrauterine insemination (IUI), obese women actually have more success than normal-weight women. No one is sure why.
What about IVF? Many jurisdictions recommend restricting treatment when women are obese. That's despite the fact that people are getting heavier. In Canada, about a quarter of the population has a BMI over 30, the threshold for obesity.
Last month, a paper by Rebecca C.H. Brown, at the University of Oxford in the UK, published a paper entitled "Irresponsibly Infertile? Obesity, Efficiency, and Exclusion from Treatment" in the journal Health Care Analysis. In it, she examined the case for excluding high-weight women. She proposes that obese people are denied IVF not because they have a reduced chance of having children or that it costs more, but rather, because negative attitudes towards heavy people make them easy targets for cost-cutting. Below, I summarize some of her main points.
Many people turn to IVF because of unexplained subfertility — that is, after two years of trying, they haven't conceived, and nobody knows why. But not everyone who wants IVF will get it, or get as many rounds as they need to succeed. Especially in publicly-funded health systems, like in the UK, there is a desire to show that a treatment both works and is worth the money.
The UK has a body, called NICE, which advises the National Health Service about which services it should and should not provide. It uses evidence to weigh cost and benefit. In the end, though, NICE provides only advice, leaving final decisions, about who gets what treatments, to local officials.
NICE recommends, for instance, that women under 40 with unexplained subfertility get three rounds of IVF. (Older women, aged 40 to 42, should get only one.) Nowhere does NICE suggest that obese women should receive fewer funded cycles, but they do advise that obese people be told that excess weight could be contributing to the problem and that they should aim for a BMI below 30.
However, according to Rebecca Brown, an ethicist at the University of Oxford, local officials do restrict treatment for obese women. In Northern Ireland, the upper limit on BMI tends to be 35, she writes, and in England, Scotland and Wales, it tends to be 30. Brown points out that other places take similar positions: in Australia and New Zealand, published guidance suggests a BMI of 35 should be the hard stop. Many US clinics also have cutoffs, and although the Canadian Fertility and Andrology Society doesn't recommend limits, a 2014 survey suggested half of all Canadian clinic directors imposed them anyway.
Why? Brown examines three possible reasons in the UK setting. One: maybe IVF is futile for the fat. Two: maybe IVF just isn't as cost-effective for them as for others. Or three: maybe there's some other reason.
Brown defines futile in this case as certain not to result in the birth of a child — or at least vanishing unlikely to do so.
She quickly dismisses this as the reason for withholding IVF, pointing to a large study which found that obese women were almost as likely as normal-weight women to have success.
[Specifically, this study, using data from the Society for Assisted Reproductive Technology (SART) looked at 239,127 fresh IVF cycles, including more than 6000 cycles in obese women with BMIs between 30 and 40, and 1000 in women with BMIs over 40. The study found that live birth rates were lower for obese women, but not by much. Normal-weight women had a 31.4 per cent chance of live birth, women with BMI 30-34.9 had a 28 per cent chance, women with BMI 40-44.9 had a 24.3 per cent chance, and even the heaviest of women, with BMIs greater than 50, had a 21.2 per cent chance of giving birth to a baby following IVF.]
So, futile it is not.
Because the NHS is a publicly-funded healthcare system, treatments need to be cost-effective. In a group of people with unexplained subfertility, you would want to be able to show that the expensive treatment results in more live births than, say, just continuing to have sex.
Typically, the way you'd do that would be to run a randomized controlled trial. Half of the participants would get the treatment and the other half would just think they got the treatment, and all of the people would continue to have sex. The success of IVF would be judged by the number of additional babies born in the treatment group as compared to the control group.
Brown finds, however, that there haven't actually been any convincing studies of this kind. A Cochrane study — a study that brings together all the different studies on a subject and tries to draw conclusions on the body of work — concluded that there wasn't enough evidence to say. [I am still gobsmacked by this: we still don't know if IVF works better than nothing in people with unexplained subfertility.]
She points out that if you want to argue that IVF for the obese is insufficiently cost-effective, the implication — since you are offering it — is that it is cost-effective for the non-obese. But that has never been established.
"This does not mean that obesity has no impact on cost-effectiveness of IVF treatment," she writes, "nor that weight loss is not a desirable occurrence in obese women... Instead, it indicates that the current policy... is not based on rigorous assessment of cost-effectiveness..."
There have been financial pressures on the NHS, Brown notes, and fertility services have been hard hit. There is evidence that many people do not consider subfertility a disease, so it may not be a priority for healthcare funding. There is also evidence of a strong bias against overweight people. Even doctors reportedly associate obesity with poor hygiene, noncompliance, hostility, dishonesty, a lack of self-control and laziness.
Research suggests that weight and weight loss are not as easy to control as many people assume. Further, any given individual who is both obese and subfertile may be subfertile for reasons that have nothing to do with weight, and we don't know which individuals these are.
You would imagine that excluding people from treatment because of stigma would be impermissable, she writes, but there is no specific protection against it. In fact, there is a strong feeling that obese people are "morally responsible" for their subfertility, she writes.
Obese people, Brown proposes, may just be a "soft target" for cuts.
"I cannot establish that this is the case here, but have instead sought to show that the evidentiary basis of this policy is weak, that healthcare commissioners are under severe financial pressures, and that both fertility treatment and obese people may be publicly unpopular."
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