Why one embryo may be better than two

Embryo,_8_cellsWhen it comes to embryo transfer, some people still worry that putting one back will reduce their chances of success. In fact, for those who have good quality embryos putting them both back will just increase your chances of having a multiple pregnancy – and although twins or triplets may sound like a wonderful idea when you are trying to conceive, it is the biggest health risk from fertility treatment. Now, some interesting new research suggests that perhaps it isn’t just those who have good embryos who should be having one embryo transferred.

A study by scientists at Nurture in Nottingham found that putting back one low quality embryo alongside a high quality one reduced the chance of becoming pregnant by more than a quarter. It was only when neither of the embryos were good quality that putting back two actually increased rather than decreased the chances of a successful pregnancy. You can read more about the research here.

This does back up the idea that single embryo transfer is the best option for many – but not all – fertility patients. It should always be something you discuss with the team treating you but it is really important to be aware that putting back more than one embryo may not increase the chances of success.

Why multiple birth rates matter

I’ve had a couple of questions recently from people about success rates at fertility clinics, and it is clear that one thing that sometimes gets overlooked when you are considering the relative merits of different places is the multiple birth rate. In fact, it’s just as important to look at this as it is to look at the overall success.

In the UK, clinics are actively trying to reduce their multiple birth rates as they recognise that this is the biggest health risk from IVF – the idea of twins can sound marvellous, but a multiple pregnancy can bring serious risks for both mother and babies. The overall multiple rate after IVF has gone down in the UK from one in four babies to one in six, and yet success rates have remained stable. This shows that by selecting the right patients for single embryo transfer, you can maintain good success rates while at the same time reducing the risks. If you want to know more, the One at a Time website is the best place to start.

Some clinics overseas do still routinely put back three or more embryos – I came across a young couple a while ago who’d had five embryos transferred. This isn’t a sign of a good clinic trying to help you to get pregnant, but rather of a clinic which may not have your interests at heart. Even within the UK, multiple rates can vary hugely, so do check them out and remember that a really good clinic will have a good success rate combined with a low multiple rate.

Multiple pregnancy and fertility treatment

It can be tempting to imagine that a multiple pregnancy might be the ideal outcome after fertility treatment – an instant family and no need to pay for any more IVF in the future. In fact, multiple pregnancy is the biggest health risk from fertility treatment, and the terribly sad story of the woman from Arizona who died shortly after giving birth to quadruplets shows just how risky it can be.

Here in the UK, the multiple pregnancy rate after fertility treatment is declining and clinics are encouraged to think carefully before transferring more than one embryo to younger women in particular. Women’s bodies are made to carry one baby at a time, and the biggest danger from a multiple pregnancy is that the babies will be born early – which carries all kinds of long-term health risks.

If you want to know more about the evidence on multiple pregnancy and fertility treatment, you should visit www.oneatatime.org.uk

Single embryo transfer just as successful…

A new study reported in the Guardian shows that putting back just one embryo at a time during IVF doesn’t reduce the chances of having a baby.  It is now policy in the UK to encourage transferring just one embryo whenever appropriate in order to reduce the risks associated with multiple pregnancies and births, but there has been some opposition from those who believe that this will inevitably reduce the chances of having a baby.

The study presented at the British Fertility Society annual meeting in Liverpool focused on live birth rates at the Leicester Fertility Centre during separate periods before a single embryo transfer policy was adopted and afterwards – and found that there was no difference in the number of women who became pregnant, and an increase in the live birth rate – which should be hugely reassuring to anyone who is worried about the single embryo transfer policy.

Of course, when you are going through fertility treatment you want to maximise your chances of success – and some clinics still try to convince patients that this will be done by transferring more than one embryo at a time.  This study shows that it really isn’t the case for all women, and transferring a single embryo for those who are most likely to be successful will not reduce the chances of success but will reduce the chances of a potentially risky multiple pregnancy.

You can read more here