Fresh or frozen?

An interesting new piece of research has looked at the effectiveness of freezing all the embryos created during an IVF cycle and then replacing them in a later cycle where no stimulation has been used.  It seems there are concerns that when you stimulate the ovaries, this may have an impact on how well the lining of the womb receives embryos. Not only this, but replacing frozen embryos in a later cycle also reduces the risk of hyperstimulation (OHSS).

The suggestion is that freezing embryos and transferring them later could actually increase pregnancy rates and also make IVF far safer for women by cutting the risk of hyperstimuation - although most women who get OHSS have fairly mild symptoms, it can be extremely dangerous.  Now, researchers from Spain have reviewed all the relevant studies in this area and analysed the results, coming to the conclusion that the chance of a pregnancy is as much as 30% higher if all the embryos are frozen for a later transfer rather than transferring them right away.

As is often the case with these rather interesting news stories, those responsible for the study have said that more research is needed to confirm their findings before making any changes to routine treatments for patients - but it will be reassuring for anyone who is having frozen embryos transferred. We often assume that this reduces the chances of success, but the evidence seems to suggest it could be quite the opposite.

The benefits of using frozen embryos

I'm just back from the annual meeting of the British Fertility Society where there were some fascinating presentations, including one detailing some new research about babies born from frozen embryos. Researchers found that babies born from frozen embryos are heavier and have a longer gestation than babies born after fresh IVF cycles - and are therefore more likely to be healthier.

It's important news at the current time when more and more people are putting back one embryo at a time and using freezing techniques. We often assume that using fresh embryos must be better when possible, but this new research suggests that may not be the case. It isn't yet certain why frozen embryos do so well, although previous research had suggested that it was linked to the fact that only the strongest, healthiest embryos would survive the freezing and thawing process.

Whatever the reasons, this is reassuring news for anyone having fertility treatment. You can read the press release from the British Fertility Society here.

Why freezing embryos is worthwhile

If you've had IVF treatment, you'll probably appreciate why freezing any spare embryos is a good idea - it gives you another chance to try to conceive in a less invasive (and cheaper) way than a full IVF cycle. However, some primary care trusts don't include the cost of freezing and transferring any spare embryos when they fund an IVF cycle - so if you can't afford to pay for it yourself, you won't have an opportunity to use all your embryos. It has always seemed wrong to me to agree to fund the treatment to create the embryos, but not to pay for their storage and use.

Now, there's more evidence to show that embryo freezing really does make all the difference to IVF success rates. Researchers at the Oxford Fertility Unit have shown that the chances of getting pregnant are fifty percent higher when you freeze and transfer spare embryos, which surely illustrates that it is not just sensible but also cost effective to fund freezing programmes.

There's more on the subject here

Good news for frosties

I was fascinated to read that new research from Denmark has shown that babies born after frozen embryo transfers tend to weigh more, and to be less likely to be admitted to neo-natal units than their fresh counterparts. Freezing embryos is an everyday part of IVF, and yet the idea of a life being frozen in time is still quite extraordinary when you think about it.

When I started having fertility treatment about 13 years ago, some fertility experts were still suggesting that freezing embryos was potentially risky as we didn't know whether it would have any long-term side effects. Some patients chose to discard frozen embryos rather than "risk" freezing them. When I found I was pregnant after a frozen embryo transfer, I had to keep reassuring myself that the thousands of babies who'd already been born that way hadn't shown any adverse outcomes.

Now, this Danish study suggests that in fact frozen embryos may be stronger because they have to survive the freezing and thawing process, and that only the toughest will do this. You can read more here

Spare embryos

There's been some controversy over the revelation that more than a million embryos have been created during fertility treatment and destroyed. Figures released by the Department of Health during the debates over the new Human Fertilisation and Embryology Bill showed that 1.2 million embryos have been destroyed in the last fourteen years.

This led to calls for more couples to donate any spare embryos to others, which is undoubtedly a good idea for those who feel able to do this, and to some criticism of this "wastage". It is vital to understand that most couples going through IVF would choose to freeze any spare embryos they produce, and that the main reason for the destruction of spare embryos is the simple fact that they are not considered viable.

Perhaps the best way to prevent spare embryos being destroyed is to improve the IVF process.
In the future, more doctors may be interested in "soft" IVF which uses lower doses of drugs to stimulate the ovaries. This produces fewer eggs, and therefore fewer spare embryos, and is not only cheaper but has the added advantage of being safer for women going through fertility treatment.