Having a multiple birth (twins, triplets or more) is the single greatest health risk associated with fertility treatment. Multiple births carry risks to both the health of the mother and to the health of the unborn babies. Twins or triplets are more likely to be premature and to have a below-normal birth weight. 20.8 in 1000 twin births involve the death of a child versus approximately 8 in 1000 singleton births.
It may seem that the actual figures for twins affected by disability or death are relatively small (for example, the risk of cerebral palsy is 8 in every 1000 twins). However, several studies have shown that twins are between 4 and 6 times more likely to suffer from cerebral palsy than singletons. Both children may be affected, which means caring for two with a disability, as well as lifelong problems for them both.
See the National Health Service online Health Encyclopedia on cerebal palsy for more information.
If you are a suitable patient, the risk of having twins is greatly reduced by having single embryo transfer (SET) without significantly affecting your chance of becoming pregnant, giving you a much clearer choice.
While single embryo transfer may have some effect on your chances of becoming pregnant, it does not halve them, particularly if:
A paper published in 2008 concluded that selective single blastocyst transfer in women with a good chance of becoming pregnant can reduce the chances of having a multiple pregnancy after IVF while maintaining the overall likelihood of becoming pregnant.
Other recent evidence suggests that transferring a single blastocyst on day 5 of in vitro culture is associated with a higher clinical pregnancy rate, compared with transfer of a single cleavage-stage embryo. Culturing the embryos until day 5 helps embryologists to identify the embryos most likely to result in a successful pregnancy.
In these two studies, an important factor in the success rate was that single blastocyst transfer was restricted to a highly selected group of women with a good chance of becoming pregnant with IVF and therefore at greater risk of multiple pregnancy.
However, blastocyst transfer may not be suitable for all women and not all UK clinics are able to provide it. Different clinics have different policies and working arrangements. Ask your clinic whether they offer this service and how they decide who is suitable for it. You should also bear in mind that if you opt for blastocyst transfer:
No. The problem is that there are too many premature IVF twins being born with serious health problems in many cases. These very ill babies could have had a healthy start in life if they had been born as singletons. This is therefore an avoidable problem. There is very little impact on your chances of a live birth as long as:
However, there is a dramatic reduction in your chance of having twins, with all the health complications this can bring for both mother and children.
NHS funded treatment
The policies of PCTs and Health Boards vary so you should find out whether you are able to access NHS funding for any further treatment (for example, the transfer of any frozen embryos from the initial fresh cycle and/or more full cycles of IVF/ICSI) if you do not get pregnant after the first single embryo transfer.Privately funded treatment
If you are paying for your treatment, check with your clinic to establish exactly what your treatment includes. You may have to pay for follow-up treatment if your clinic does not include the cost in your initial treatment. To be absolutely clear about all the costs involved, ask your clinic for a personalised, costed treatment plan before beginning any treatment. See Funding for more information.
If you get pregnant with the first, fresh embryo, you would not normally pay additional costs.
However, if you need further treatment with frozen embryos, there may be an additional cost (you should check this before you begin treatment), but it certainly should not double the original cost.
If you are receiving treatment under the NHS, you should check whether the cost of storage and frozen embryo transfer is covered by your Primary Care Trust (PCT) or Health Board. If you are receiving private treatment check with your clinic to establish exactly what your treatment includes (see 'Will I have to pay for further treatment' above).
The embryologist uses a system of grading to select the embryo that is most likely to result in a successful outcome. See Embryo grading for more information.
Normally, other embryos that are considered to be of good quality by the embryologist, will be frozen and stored in case they are needed in a follow-up treatment, either because the first transfer sadly fails or if it is successful and you return for further treatment later. These embryos are frozen and then stored in tanks of liquid nitrogen. A liquid called a cryoprotectant is added to protect the embryos during freezing.
Not all embryos survive freezing and subsequent thawing, so when you come to your next treatment cycle, your clinic may advise you to have more embryos thawed than can be transferred.
Frozen embryos can be stored for up to 5 years, but this may be extended to up to 10 years under certain circumstances (for example, if the woman is over 55).
Due to the freezing and thawing process, your chances of having a baby using a thawed frozen embryo are slightly lower than with a fresh embryo. However, your chances of becoming pregnant with a thawed frozen embryo are not affected by storage times.
Normally, women considered to be most at risk of multiple pregnancy are those under 35 but your clinician will take into account a number of factors when deciding whether you should be offered single embryo transfer (SET). You should talk to your clinician about your particular risks.