Fertility foods, supplements and add-ons: myths and facts

A pineapple holding some McDonald's chips

I'VE READ THE CLAIMS, DUG DEEP INTO THE SCIENTIFIC RESEARCH, AND COME OUT THE OTHER SIDE! My aim is to help you make the right decisions for YOUR treatment, without spending another moment on a confusing or inaccurate message board thread.  

Here’s a full list of everything you’ll find in this article:


Alternative therapies/supplements:

Conventional wisdom:

“Add-ons” offered by clinics

I’m not a health professional and I don’t know about your specific condition or treatment protocol, so please get a second opinion from your fertility doctor if you feel you need it.

Before we get started…

Questions to ask your doctor at every stage of IVF treatment: free downloadable guide

IVF isn’t just overwhelming; it can also be a mind-boggling and sometimes terrifying experience because there’s so much to learn and so many rules to follow.

Problem is, doctors are busy – and they often don’t have the time to anticipate your concerns and provide all the information you might need.

This downloadable guide contains questions that will help you understand the process better, get the answers you deserve, and feel more in control of the situation (and your rights as a patient).

Enter your email address to receive it right away.

I won't send you spam. Unsubscribe at any time.

Pomegranate juice

The tip: drink pomegranate juice throughout the IVF process.

The claim: pom juice is supposed to beef up the lining of your uterus and improve blood flow (including blood flow to the uterus). It’s also meant to improve sperm quality in men.

The science: there’s basically no evidence for any of this. Everything is supposition: “Because pomegranate contains such-and-such vitamin, we imagine it might help with x.”

Some people claim it’s the antioxidant properties of pomegranates that help most when it comes to fertility. Antioxidants “clean up” waste products in our cells (called free radicals) before those waste products can do harm. Free radicals can be caused by outside sources like smoking and toxins, but many come from the everyday functioning of our bodies.

Antioxidants are both produced by the human body and found in food like pomegranates, but they’re also found in heaps of other brightly coloured fruit and veg – so I’m not sure why everyone in IVF Land goes crazy over pomegranates. More importantly, there’s practically zero evidence that any antioxidants help with fertility anyway.

Bear in mind that pomegranates emerged as a “wonder food” at the same time as a massive PR campaign by POM Wonderful – which makes and sells pomegranate juice.

The verdict (based on the evidence so far): waste of time.


The tip: eat pineapple core on the days following embryo transfer.

The claim: pineapple (particularly the core) contains bromelain, which helps to prevent blood clots. According to some, this means it could help with blood flow to the uterus. Improved blood flow makes the uterus healthier and a better environment for implantation to occur.

The science: It’s true that improved blood flow to the uterus creates a better environment for implantation to occur. But is there any evidence that bromelain/pineapple actually does this? No.

The verdict (based on the evidence so far): waste of time.

Brazil nuts (for men)

The tip: men should eat Brazil nuts every day to improve their sperm.

The claim: Brazil nuts are an excellent source of selenium, which is necessary for the formation and development of sperm.

A small 1998 study (69 participants) found that when sub-fertile men were given selenium supplements for three months (100 micrograms per day – equivalent to 1.5 Brazil nuts), their sperm motility increased significantly.

The science: while 69 participants is a very small sample indeed, this evidence is convincing because we already know that selenium is necessary for sperm health (whereas with pineapple, for example, we don’t necessarily know that bromelain is necessary for uterine health).

The verdict (based on the evidence so far): worth it.

Brazil nuts (for women)

The tip: women should eat Brazil nuts while trying for a baby.

The claim: research from 2014 discovered that large, healthy follicles in the ovaries tended to be higher in selenium.  

The science: there’s nothing to suggest that the selenium we eat translates into the selenium produced in our ovaries (in the same way that eating large amounts of cholesterol-rich foods doesn’t necessarily mean we have high levels of “bad” cholesterol in our bodies).

The verdict (based on the evidence so far): the science is sketchy, but there’s no harm in trying – just in case.


The tip: stick to full-fat dairy while trying for a baby.

The claim: in the 1990s, a single study by the Harvard School of Public Health looked into the impacts of dairy on women who’d attempted pregnancy or become pregnant during an eight-year period.

The results showed that the women who consumed higher amounts of low-fat dairy products were more likely to have ovulatory infertility than those who consumed higher amounts of high-fat dairy products. The difference was even more pronounced for women who consumed high amounts of low-fat sherbet (?!) and frozen yoghurt.

(“Ovulatory infertility” is when you don’t ever ovulate or you ovulate infrequently/irregularly.)

The science:

  1. Hang on… so THOUSANDS of articles suggesting that you “consume high-fat dairy for increased fertility” are based on ONE study done in the 90s?
  2. Is it not possible that people who consume tons of low-fat/no-fat dairy products are more likely to have an unhealthy relationship with food in general – and are therefore more likely to be underweight or overweight? Something we know for sure is that a woman’s weight has a significant impact on ovulatory infertility. (For more information on weight and fertility, read this article on fertility diets.)
  3. The study says nothing about women who don’t have ovulatory infertility, yet many articles and posts recommend high-fat dairy as something that will improve everyone’s chances of conceiving. This isn’t the fault of the people who wrote the study, of course, but it still means lots of readers are being misled.
  4. The writers of the study did acknowledge that high-fat dairy doesn’t necessarily lead to better fertility outcomes: it could just be that low-fat dairy products (which are often spiked with a range of artificial ingredients and sugar) contain something that’s detrimental to fertility.

    If this is the case, eating a high-fat-dairy diet won’t lead to any better fertility outcomes than sticking to a no-dairy diet. I’m not saying that these other ingredients are the real cause of ovulatory infertility – just pointing out that if there is a genuine link between low-fat dairy and fertility, it might not be the “dairy” aspect that’s the problem.
  5. On a similar topic, what about countries where dairy – whether high fat or low fat – simply doesn’t feature much in the national diet? Do they have higher rates of ovulatory infertility? I can’t seem to find any stats, but I’d love to know.

The verdict (based on the evidence so far): waste of time.


The tip: steer clear of coffee while trying for a baby.

The claim: coffee, for whatever reason, lowers your chance of success – regardless of whether you’re trying to get pregnant naturally or with fertility treatment.

The science: there have been quite a few studies and they all have slightly different remits and purposes. Some look at caffeine while others restrict their remit to coffee specifically, for example. And some will look at the effects on IVF, while others will examine fertility levels in general (and others still will look at the effects on the growing foetus). And so on.

I’ve looked at a lot of them, and here are a couple of noteworthy findings:

  • A 2012 Danish study found that women who drank five or more cups of coffee a day were 50% less likely to get pregnant through IVF. Having four cups of coffee or fewer made no difference to IVF success rates (that is, it should be fine to drink up to four cups of coffee a day while doing IVF).
  • A 1998 study of the effect of caffeine on pregnancy couldn’t find an association between coffee or caffeine consumption and a reduction in fertility. The researchers did, however, discover that drinking half a cup or more of tea per day doubled the odds of conception each cycle. They suggested that lifestyle factors associated with coffee/tea drinking could play a part rather than caffeine. (Another study found that coffee drinking reduces fertility only in smokers – yet they pointed out that another separate study showed that tea drinkers smoked less than coffee drinkers.)

While there’s no clear evidence that caffeine affects the ability to become pregnant naturally or through IVF, most researchers recommend that you limit your intake to one or two cups of coffee per day – just to be on the safe side. (But most stress that there’s no benefit in reducing consumption to zero.)

I’m inclined to think the Danish study demonstrated correlation rather than pure causation (i.e. those who drank five or more cups possibly had stressful and physically demanding jobs – and that’s the reason for struggling to get pregnant rather than how much coffee they drank to stay awake), but the researchers didn’t reach that conclusion by themselves, so it’s just pure supposition on my part.

The verdict (based on the evidence so far): it’s worth cutting down to one or two cups a day (200mg of caffeine in total), just in case. And remember that fizzy drinks also contain caffeine.  

As for why caffeine might (and remember it's just a “might”) affect your chances of getting pregnant… there are so many different hypotheses, from “it affects blood flow” to “it has an impact on the nervous system”. No one knows, basically. 

Doctors also recommend that you drink no more than 200mg of caffeine throughout pregnancy: some studies have found links between high caffeine intake and low birth rate, premature birth, and miscarriage. A 2015 Cochrane review of randomised controlled studies couldn't confirm that those links exist, but again: you might want to reduce your intake just in case. (Cochrane is a British charity that organises medical research findings in order to help professionals, patients and policymakers make evidence-based choices about health interventions.)

Questions to ask your doctor at every stage of IVF treatment: free downloadable guide

IVF isn’t just overwhelming; it can also be a mind-boggling and sometimes terrifying experience because there’s so much to learn and so many rules to follow.

Problem is, doctors are busy – and they often don’t have the time to anticipate your concerns and provide all the information you might need.

This downloadable guide contains questions that will help you understand the process better, get the answers you deserve, and feel more in control of the situation (and your rights as a patient).

Enter your email address to receive it right away.

I won't send you spam. Unsubscribe at any time.

McDonald's chips

The tip: eat McDonald’s chips.

The claim: eating McDonald’s chips after sex (or embryo transfer) will help you get pregnant. There isn’t much information online other than that, but both IVFers and perfectly fertile women are downing them by the bucketload anyway.  

The science: It’s hard to trace how this advice came to exist in the first place. From piecing together various anecdotes and articles, here’s what I think might have happened:

  1. In the US, doctors often advise women to increase their salt intake after egg retrieval (not embryo transfer) if they’re at risk of getting ovarian hyperstimulation syndrome (OHSS). Their logic is that egg retrieval often causes excess fluid to hang around in your abdomen, and the salt will – through osmosis – encourage the fluid out of your abdomen and into your bloodstream.

    In the UK, doctors give the exact opposite advice: don’t increase your salt intake, and be sure to increase how much water you drink, in order to bring much-needed fluid back into your bloodstream.

    (For the science behind both theories, read my article on how to avoid or treat OHSS.)
  2. Somehow, through a transatlantic game of Chinese whispers, this must have happened:

    American doctor tells IVF patient: “Have more salt after egg retrieval to help prevent OHSS.”

    American IVF patient (who blogs about infertility in her spare time): “Okeydokes, doc, will do. Ooooh McDonald’s fries! They’re salty: I’ll eat those. And I’ll blog about it to tell everyone what the doctor recommended.”

    British IVF patient (who reads a lot of blogs about infertility in her spare time): “Hmmm… seems I should eat McDonald’s chips after egg retrieval. I’ll tell everyone in my Facebook fertility group: they’ll definitely want to know about this.”

    Person in Facebook fertility group: “Iiiinteresting that eating McDonald’s chips will help improve my chances of pregnancy. I’ll try it after embryo transfer and see what happens.”


    [Gets pregnant]

    To her friends on a night out: “Guys, guys! I ate McDonald’s chips after my embryo transfer and now I’m pregnant!!!” You all need to try this if you’re hoping to have a baby.”

    Those friends (who don’t have any fertility problems), when they get back home to their partners: “As soon as we’ve had sex tonight, we’re going out to McDonald’s. OK?”
  3. Everyone becomes obsessed with eating McDonald’s chips (whether they have fertility problems or not) to help get pregnant.

The verdict: waste of time.


The tip: acupuncture improves your chances of IVF success.

The claim: the theory is that acupuncture increases blood flow to the uterus. This can make the lining of the uterus more receptive to the embryo being transferred – which makes successful implantation more likely.

Some also believe that acupuncture relaxes the cervix, which also helps with embryo transfer.

The science: as mentioned in the “pineapple” section, it’s true that improved blood flow to the uterus creates a better environment for implantation to occur. But does acupuncture actually help this happen?

A few studies and things to consider:

  • Cochrane’s 2013 research into fertility acupuncture concludes: “There is no evidence of benefit for the use of acupuncture in participants undergoing assisted conception treatment around the time of embryo transfer or at egg collection in terms of improving the live birth rate, ongoing or clinical pregnancy rate.”

    It did acknowledge that acupuncture doesn’t seem to do any harm, at least: “There is also no evidence that acupuncture has any effect on miscarriage rate or had significant side effects.”
  • In 2010, the British Fertility Society said: “… there are no published randomised controlled trials on the effectiveness of using Chinese herbal medicine in conjunction with fertility treatment and therefore the guidelines conclude there is currently no evidence to support the use of this in fertility treatments”.
  • In 2008, the NHS published an article in response to newspaper stories claiming that acupuncture “can increase the chances of getting pregnant for women undergoing fertility treatment by 65%”.

    The NHS article states (among other things):

    1: “Although the methods used by this study are robust, some possible biases cannot be ruled out. Studies that have negative results are less likely to be published and may therefore not have been included.

    2: “… the study found that the additional benefit of acupuncture depended on how successful IVF was overall. Where pregnancy rates were high, acupuncture had little benefit.”

    3: “An interpretation of the 65% benefit quoted by the papers must be considered in light of the fact that they represent relatively small absolute benefits considering that the rates of pregnancy in the non-acupuncture groups were high.”
  • A 2018 study of 848 women in Australia and New Zealand showed that there’s no difference between “real” acupuncture and “sham” acupuncture (using blunt needles) when it came to live birth rates in IVF patients.
  • It’s difficult to control for age, lifestyle factors, general health, etc. when comparing different studies and their results. One study might only include women under the age of 30, while another might include anyone up to the age of 40 – to give just one example.
  • If we set aside the distrust of acupuncture by the NHS, the British Fertility Society and Cochrane (among others) and we decide to believe that acupuncture is helpful, we don’t necessarily need to believe it’s due to physical effects. For example, Caroline Smith, the chief investor of the Australia/NZ study, says acupuncture – despite her findings – could still be worthwhile: “Some studies suggest reproductive outcomes may be improved when acupuncture is compared with no treatment”, due to the “psycho-social” benefits of acupuncture.

The verdict (based on the evidence so far): if you enjoy acupuncture and find it relaxes you, there’s no harm in continuing (although the evidence is mixed on whether “relaxing” helps with conception).

But if you don’t enjoy it and/or you struggle to afford it, you can rest assured that it’s (probably) not helping much anyway.


The tip: take DHEA (dehydroepiandrosterone) if you have a poor ovarian reserve (i.e. you have a small number of eggs, and those eggs are poor quality).

The claim: DHEA is a steroid that naturally exists in men and women, and its levels decline with age. The female body converts it into oestradiol (a form of oestrogen) as well as male steroid hormones called androgens (such as testosterone).

While androgens are male hormones, they’re essential for the production and development of healthy eggs in the female body.

Women with PCOS (polycystic ovary syndrome) have lots of follicles and higher androgen levels, so in the early 2000s, it was hypothesised that women with smaller amounts of follicles could benefit from supplemental androgens.

The science: when doctors started giving DHEA to women with a poor ovarian reserve, the evidence looked promising: their androgen levels increased accordingly. Not only that, but these women started to produce more eggs – and better-quality ones at that. High-quality eggs have a better chance of developing into embryos, implanting in the uterus, and avoiding miscarriage.

Before starting IVF treatment, many clinics now give DHEA to women with a poor ovarian reserve. They wait about three months until the DHEA has done its thing – increasing androgen levels to appropriate levels – and then begin IVF, with the expectation that the eggs being produced for IVF cycles will have a better chance of developing well. (Often, women continue taking the DHEA after IVF treatment has begun – right up until they get a positive pregnancy test.)

Why not just bypass the DHEA phase and give testosterone instead? There are a few scientific reasons, but also the issue of side effects: testosterone supplementation comes with some bad ones, whereas most women tolerate DHEA much better.

So… all good, right?

Obviously not: when has science ever been that easy?

There have been many criticisms of the studies conducted so far, relating to the small number of participants, the style of study conducted (the vast majority aren’t randomised controlled trials – the gold standard), changing definitions of conditions halfway through, poor/incomplete evidence, and more. (This article provides a nice summary of the criticisms.)

As a result, most analyses of DHEA studies have been reluctant to make any positive claims about it. To paraphrase them all: “We don’t know for certain about DHEA because the studies have been conducted badly, but we think there might be benefits to taking it if you have a poor ovarian reserve. Also, it seems to work best if you’re under the age of 41. Again, though, we really don’t know, and we can’t say anything for certain.”

But as DHEA is inexpensive, has minimal side effects, and might just work, why not take it anyway – just in case?

Well, plenty of doctors do prescribe DHEA. In fact, approximately one-third of IVF clinics worldwide now prescribe DHEA to patients who they think would benefit.

But “patients who they think would benefit” is the key thing to remember. Women with PCOS, for example, almost certainly don’t need DHEA. They already have elevated levels of androgens, and their PCOS symptoms (such as acne and excess hair) are only going to get worse with DHEA.

You also need to get the dosage right. Too much DHEA in anyone may lead to unwanted side effects – some of which may well be irreversible. It’s been shown to decrease levels of HDL (“good”) cholesterol in women and has also been linked (unproven, so far) to increased risk of heart attack, heart disease, and metabolic syndrome.

It’s important to mention that DHEA is classed as an “unlicensed” medicine in the UK, which means it has a license for specific use in another country, but not the UK. Doctors are still able to prescribe it, but they’ll only do so after carefully considering all the options available. (The official guidance from NICE to medical establishments is currently anti-DHEA: “Do not use growth hormone or dehydroepiandrosterone (DHEA) as adjuvant treatment in IVF protocols.”)

The verdict (based on the evidence so far): worth a try if you have a poor ovarian reserve – but only if it’s been prescribed by a doctor who knows your complete medical history.

It’s possible to buy DHEA online from countries where it’s sold over the counter, but that seems like a potentially disastrous (including legally disastrous) idea!


The tip: take CoQ10 for better-quality eggs.

The claim: all the cells in our body contain tiny little structures called mitochondria, which work to keep the cells full of the energy they need for life, repair and regeneration. The reason these mitochondria have energy in the first place is thanks to CoQ10 – an enzyme that lives in the mitochondria and helps convert the food we eat into energy. (This energy is called Adenosine Triphosphate, or ATP.)

As we age (particularly after the age of 30), it’s believed that our naturally occurring levels of CoQ10 start to diminish. Consequently, the processes that require lots of energy (such as fertilisation and embryo development) can’t work as hard. With less energy available, errors creep in – leading to problems such as genetically abnormal (i.e. “low quality”) embryos.

Plenty of foods contain CoQ10, but the amounts are minimal – and that’s why some scientists and medical professionals recommend that people take CoQ10 supplements too. This advice isn’t just for those who are hoping to have a baby: it pretty much applies to anyone who’s getting older (which is, uh, everyone).  

CoQ10 isn’t a one-trick pony: it also functions as the body’s primary antioxidant. When we’re talking about CoQ10 and its role in fertility, though, we’re mainly talking about its role as an energy producer.

The science: anecdotally, the results for women doing IVF are spectacular: women on fertility message boards around the world are discussing how CoQ10 helped improve their egg quality.

The scientific evidence, however, is inconclusive. A few studies have suggested that CoQ10 may improve egg quality in mice, but we’re not mice. The only human study conducted so far (that I could find, anyway) didn’t find a statistically significant difference between those who took CoQ10 and those who didn’t.  

Something to be aware of: there is evidence that CoQ10 helps with male fertility problems. You can read more about that here.

The verdict (based on the evidence so far): you may as well give it a go, but don’t expect it to be a miracle cure. Also, be aware that there’s been no research into the safety of CoQ10 on unborn babies, so you should stop taking it if you find out you’re pregnant.

Of the doctors who recommend CoQ10, most suggest that you take 300–600g daily, starting about three months before you’re due to begin IVF treatment.

One last thing: if you read any “YAY CoQ10!!!” message board threads, you’ll probably have come across references to “ubiquinone” and “ubiquinol”. Ubiquinone is the same thing as CoQ10. The body converts ubiquinone into ubiquinol and vice versa to maintain a constant state of equilibrium between the two, as both types perform important functions.

Until recently, it was only possible to buy CoQ10/ubiquinone. That all changed in 2006 when ubiquinol became commercially available.

Ubiquinol is the type that’s needed to maintain the cell’s energy levels, and therefore many argue that you should buy it instead – as you don’t need to wait for the body to convert CoQ10 for you. The jury’s out on this: some argue it’s just a marketing ploy by the makers of ubiquinol (which is far more expensive), and the body is perfectly cable of converting CoQ10 by itself. Many others believe ubiquinol to be far superior.

Bed rest after embryo transfer

The tip: stay lying down/in bed for two or three days following embryo transfer.

The claim: limited activity (and limited upright activity) helps the embryo attach to the uterus lining and implant there.

The science: multiple studies have shown this to be absolute rubbish: pretty much all conclude that there’s no statistically significant difference in pregnancy rates between those who rest and those who don’t.

Surprisingly, some studies indicate that bed rest (even just ten minutes) could actually be detrimental to IVF success. (The most recent study found that bed rest for more than 20 minutes immediately after embryo transfer was associated with a 15% reduction in the chances of clinical pregnancy.) While more research is needed on this particular finding, it’s widely accepted that staying active after embryo transfer doesn’t negatively affect pregnancy rates.

Also, remember that implantation doesn’t occur until seven or eight days after fertilisation – and the process can then take up to a week for the embryo to fully implant. If a three-day embryo is being transferred into your uterus, the “bed rest” advice would only make sense if at least five days of bed rest were being recommended. And yet… no doctor is advising you to have that much downtime.

One reason “staying active” might actually help matters is due to blood circulation. When we move, blood circulation in the body improves – including circulation in the uterus. As we’ve discussed before, doctors agree that good blood circulation helps improve the lining of the uterus, which in turn helps with embryo implantation.

If you’re worried that the embryo could fall out if you get up and move around too soon after transfer, don’t be: it’s just not possible. Your uterus is a muscular organ that naturally stays contracted, and – much like a deflated balloon – it expands with the growth of your baby when you become pregnant. When there’s just a tiny embryo in there, the space is tiny – with no room to move around.

And don’t forget that your uterus lining will be thick and sticky by this point too, so there’s really no way for that embryo to come loose or fall out. One website gives the following analogy: “It’s like a grain of sand in a peanut butter sandwich.”

As well as getting up and moving around, you can also do the following after embryo transfer without worrying:

  • Cough and sneeze
  • Laugh
  • Go the loo
  • Go back to work (literally, as soon as you’ve had the transfer, if you want)
  • Fly abroad (although find out in advance about the healthcare in your destination country, just in case you need it)

Despite all the evidence, a minority of doctors still recommend bed rest after embryo transfer. Why?

It might simply be that they’re stuck in their ways. And if their clinic’s success rates are on par with national statistics, they might be scared of messing with their own advice (especially as we still can’t say for certain that bed rest negatively affects implantation rates.)

Another potential reason is that they don’t want women second-guessing/blaming themselves if they don’t get pregnant.

Is there anything you definitely shouldn’t do straight after embryo transfer? Yes – but the list is short:

  • Avoid sex for a couple of weeks (at least) if you’re having a fresh embryo transfer (ET). Your ovaries will be enlarged and sore after all that stimulation and egg retrieval, so you need to give them a little while to heal. If you had a large number of eggs retrieved or you’re at risk of ovarian hyperstimulation syndrome (OHSS), you might be told to wait longer.

    If you’re having a frozen embryo transfer (FET), you don’t need to worry. Some clinics still recommend that you refrain from sex anyway; they may well have a good reason for recommending it, but I’m not sure what it is. Ask them (and then please get back to me!).
  • Don’t go swimming for the first few days. This has nothing to do with your newly transferred embryo, but the fact that you’ve just had a catheter threaded through your cervix. You need to give it a few days to heal, to avoid the risk of infection.
  • Don’t take a bath for the first two weeks, for the same reason as swimming: to avoid infection. After those first two weeks, you can have a bath but don't make it too hot – a rule that applies throughout pregnancy and particularly during the first 12 weeks (whether pregnant naturally or by IVF).

    There's evidence (based on animal studies because it's not exactly ethical to do the studies on pregnant humans) that raising your body's core temperature might increase the risk of the baby having a neural tube defect such as spina bifida. The baby's spine develops most during the first 12 weeks of pregnancy, which is why the first 12 weeks are particularly important. Saunas, steam rooms and hot tubs are also off limits for this reason. Showers won't raise your body's core temperature unless you're there for a very long time.

The verdict (based on the evidence so far): the “bed rest” advice is a load of codswallop, and may actually be detrimental. When it comes to baths, sex and swimming, though, speak to your doctor and see what they say.

Exercise during the two-week wait

The tip: every doctor says something different.

The claim: some tell you to be on bed rest for the first few days, but we covered earlier why that’s probably not a wise idea. (Most) other doctors will tell you to limit your exercise to light activity like brisk walking. A few others will tell you to carry on as normal – even if that means running five miles a day.

One 2006 study about exercise and IVF is often cited online (because it seems to be the only study into exercise and IVF), but it covers the general exercise habits of women undergoing IVF – not the two-week wait specifically.

The science: who knows! Here are some of the reasons doctors give for telling you to restrict your exercise to brisk walking:

  • Potential reason 1: there’s a risk the embryo will “fail to implant” with vigorous exercise. But that seems to contradict everything they and others say about the structure of the uterus, how the embryo is like a “grain of sand in a peanut butter sandwich”, and so on.
  • Potential reason 2: you want to avoid getting your heart rate or core temperature up too high (due to risks of neural tube defects, as mentioned above).

    If you exercised regularly before embryo transfer, your body will be better at regulating its core temperature than someone who exercises rarely – so you can probably do something a bit more strenuous than brisk walking. Check with your doctor first, though.
  • Potential reason 3: your ovaries will be enlarged and sore after all that stimulation and egg retrieval. This reason does make sense if you’re doing a fresh embryo transfer (ET).

    There’s also a risk of a rare condition called “ovarian torsion”, which is when an ovary becomes twisted around the tissues that support it. It’s incredibly painful and can lead to the loss of your ovary. Ovarian torsion is much more likely to occur in enlarged ovaries – especially as a result of exercise or strenuous activity. 

    If you're doing a frozen embryo transfer (FET), though, this reason is irrelevant. 
  • Potential reason 4: doctors don’t want you second-guessing/blaming yourself if you don’t get pregnant.

One study tried to gauge the effect of exercise after embryo transfer, but, uh, everyone in the study stopped any form of vigorous exercise after their transfer. So… yeah… that was a waste of time.

What many doctors do say – in addition to their blanket advice to do brisk walking only – is that really, the advice needs to be customised to the person. If you run ten miles and lift weights every day, your body will be better at regulating its core temperature – plus going cold turkey will most likely make you even more stressed and angsty. While I haven’t looked into the effects of mental health on IVF success, I don’t think any doctor would agree that stress and angst are particularly beneficial for the process.

The verdict (based on the evidence so far): if exercise is important to you, find the most sympathetic doctor or nurse at your clinic/hospital, tell them your concerns about doing no “proper” exercise during the two-week wait, and ask for their opinion.

Embryo glue

The tip: hospitals and IVF clinics should use embryo glue to help the embryo attach and implant better after being transferred.

The claim: embryo glue contains a substance called hyaluronan – naturally found in the uterus – which is added to the dish in which embryos are kept before transfer. The hyaluronan both makes the embryo feel more “at home” in its petri dish and acts as a binding agent – helping the embryo attach and implant to the lining of the uterus when it's transferred.

In natural conceptions, the level of hyaluronan in a woman’s uterus increases around the time an embryo implants; it follows that adding hyaluronan to pre-transfer embryos in assisted conceptions will help with implantation.

The science: there have been many, many studies already, and most of them show humongous benefits to using embryo glue. There’s just one problem: the vast majority of studies to date have been performed by researchers affiliated with, and financially supported by, one of the many manufacturers of embryo glue competing for market share. And we could choose to believe them, but… they’re not exactly going to say it doesn't work, are they?

So instead, let’s look at what Cochrane researchers discovered. They looked at a total of 17 randomised controlled trials (remember: the gold standard) into different kinds of “embryo transfer media” – including hyaluronan. They conclude:

  • “The 14 trials reporting clinical pregnancy rates showed evidence of treatment benefit when embryos were transferred in media containing functional concentrations of [hyaluronan]… as compared with low or no use of [hyaluronan].”
  • “The multiple pregnancy rate was significantly increased in the high [hyaluronan} group”, but this “may be the result of use of a combination of an adherence compound and a policy of transferring more than one embryo”.
  • “However, the evidence obtained is of moderate quality.”

Other non-randomised controlled studies (those not affiliated with the manufacturers) reached less hopeful conclusions. Some (like this one) found that embryo glue only helps those who’ve previously had implantation problems following IVF treatment, while others (like this one) state that “Embryo glue did not seem to improve pregnancy or implantation rates. In fact, in evaluating fresh embryo transfers there was a significantly higher live delivered pregnancy rate in the women not using embryo glue (39.3%) vs those using the glue (14.3%).”

It should also be mentioned that the Human Fertilisation and Embryology Authority (HFEA), which regulates fertility treatment in the UK, is currently sitting on the fence when it comes to embryo glue:

“Research from the Cochrane review shows that embryo glue containing hyaluronan increases pregnancy and live birth rates by around 10%. There is one high quality study in this review which shows that the use of embryo glue improves pregnancy and live birth rates, other studies in the review were of moderate quality. Further high quality studies are needed before doctors can be confident of the benefits of embryo glue.”

The verdict (based on the evidence so far): if you have a history of implantation failure and a few hundred quid to cough up, you could give it a go – especially as there are no side effects. But, as always, remember that the evidence is far from conclusive – so don’t expect miracles.

Assisted hatching

The tip: ask your IVF doctor about assisted hatching if you’re aged 37 or older, or if you’ve had prior unsuccessful attempts at IVF.

The claim: in a “natural” cycle, the embryo is surrounded by a protective outer shell – called the zona pellucida – for the first fiveish days after fertilisation. This shell stops other sperm from entering the embryo and also makes sure the embryo doesn’t implant prematurely in the fallopian tube.

At around the end of the fifth day of development, the embryo is now referred to as a blastocyst, and it moves towards the uterus for implantation. As it does so, the zona partially dissolves, allowing the blastocyst to break out of its shell. This process is called “hatching”.

In an IVF cycle, embryos tend to be transferred either three days after fertilisation (pre-hatching) or about five days after fertilisation (when the now-blastocyst may well be partially or fully hatched).

Some IVF embryos fail to hatch successfully, though – and if they don’t hatch, they can’t implant in the uterus. Why IVF embryos rather than all embryos? Sometimes it’s down to the types of people who need IVF in the first place, and sometimes it’s a result of the IVF process itself:

  • According to many (but not all) scientists and researchers, older women are more likely to produce embryos with a “harder” zona pellucida, which makes it more difficult for the embryos to hatch. Because these women fail to get pregnant naturally, they’re the ones who end up getting IVF treatment.

    These women may have multiple failed IVF attempts if no one considers a “harder” zona to be a possible reason for their original fertility problems. (From what I can tell, it isn’t possible to detect if embryos have a hardened zona before transfer.)
  • Women with elevated FSH levels are also believed to produce embryos with more hardened zona pellucida. These same women also seem more likely to have multiple failed attempts at IVF, and this might be why.  
  • Frozen embryo transfers (FET) may cause the zona to harden with freezing.
  • Embryos resulting from fertility treatments such as IVF develop more slowly compared to “naturally created” embryos. This might be because something in the lab environment (the cultures used to keep the embryo alive, the chemicals, etc.) has artificially interrupted the hatching process.

    A slowly hatching embryo is almost as bad as a non-hatching embryo. As one study states: “The implantation window is the critical period when the endometrium [uterus lining] reaches its ideal receptive state for implantation. The majority of embryos hatch during this time, suggesting that a precise synchronization between the embryo and endometrium is essential.”

The aim of assisted hatching is to get over any of these hurdles and improve the chances of implantation. It’s usually performed on a three-day-old embryo, which is then transferred that same day or on day five. (If transferred on day five, the embryo/blastocyst will be partially or fully hatched.)

There are many different types of assisted hatching, but most do one of two things:

  • “Thin out” the zona – usually with chemicals, OR
  • Create holes in the zona, with the intention that it will encourage the entire shell to crack open more easily

The science: our good friend Cochrane analysed all randomised controlled trials of the process, and found that “there was some evidence that assisted hatching improves the chances of pregnancy in women for whom IVF has been repeatedly unsuccessful, but more research is needed”.

Another analysis – this time by the Journal of Assisted Reproduction and Genetics – pretty much agreed with the Cochrane analysis: “… several studies have shown no increase in pregnancy rates when assisted hatching is performed on unselected groups” (my emphasis). However, “Pregnancy and implantation rates appear to be significantly increased by assisted hatching for women with unexplained recurrent implantation failure in at least two, and usually more, previous IVF cycles.”

They went on to acknowledge that “… it would of course be preferable to identify patients who would benefit from assisted hatching before they have unsuccessful IVF cycles”. But as recurrent implantation failure is (for now) “unexplained” in most women, there’s no other way to go about it.

But if some women would benefit, why not provide assisted hatching for all women undergoing IVF – to avoid some of them undergoing repeated unsuccessful cycles?

A few reasons:

  1. It’s expensive! It costs around £500 each time and isn’t available on the NHS.
  2. The evidence is shaky that it even benefits women who’ve had multiple failed IVF attempts. For everyone else, there’s practically zero evidence – but more worryingly, there might even be evidence that assisted hatching is bad in certain situations. For example, one study found that embryos that have been frozen using the more modern method of “vitrification” (which many clinics now make use of) actually fare worse with assisted hatching. It’s probably unwise to submit embryos to hatching processes if there’s a risk the outcome will be worse than doing nothing.
  3. Importantly, very few studies measure live birth rates: they tend to just explore clinical pregnancy rates. Of the studies that did measure live birth rates, there was, according to Cochrane, “no evidence of a benefit in the live birth rate with assisted hatching”. As the Journal of Assisted Reproduction and Genetics points out, this might be because “the small sample sizes in studies reporting delivery rates have lacked sufficient power to detect a difference”, but we just don’t know.
  4. While we don’t know much about live birth rates, we do know about multiple pregnancy rates. Women who have a “poor prognosis” (and are, as mentioned, possibly more likely to benefit from assisted hatching) are far more likely to get pregnant with monozygotic twins (i.e. identical – from a single embryo) if they do indeed get pregnant. Why? Researchers think it might be because the assisted hatching technique could cause the embryo to split into two embryos around the time of implantation.

    All types of multiple-birth babies are at increased risk of a number of problems (such as premature delivery, low birth weight, congenital problems, disability and so on), but monozygotic twins are the highest-risk subgroup.

The verdict (based on the evidence so far): definitely DON’T go in for assisted hatching just because you’ve seen it on the list of “extras” on the clinic’s price list.

But if you’ve suffered from multiple failed IVF attempts in the past, it might be worth considering. (Bear in mind you can’t get it on the NHS.) The evidence is far from conclusive, though, and the list of reasons not to do it is long.

Questions to ask your doctor at every stage of IVF treatment: free downloadable guide

IVF isn’t just overwhelming; it can also be a mind-boggling and sometimes terrifying experience because there’s so much to learn and so many rules to follow.

Problem is, doctors are busy – and they often don’t have the time to anticipate your concerns and provide all the information you might need.

This downloadable guide contains questions that will help you understand the process better, get the answers you deserve, and feel more in control of the situation (and your rights as a patient).

Enter your email address to receive it right away.

I won't send you spam. Unsubscribe at any time.