Fertility experts critise new twin research

8 July 2008


Experts in fertility treatment have criticised new research which claims that women are being misled over the risks of having twins. The research undertaken by Dr Norbert Gleicher from the Centre of Human Reproduction in New York claims that  giving birth to twins is no more risky than singleton births.

His claims have met with a strong response from experts including Dr Mark Hamilton, British Fertility Society, and Rachel Cutting, Association of Embryologists, both members of the Multiple Births national strategy group, and from Prof Peter Braude, UK representative, ESHRE Committee of National Representatives, and chair of the expert group which produced the One Child At a Time report.

Statement from ESHRE chair Prof Joep Geraedts, Dr Francoise Shenfield and Prof Peter Braude.

This study is an interesting challenge to the move to reduce twin births after IVF. It correctly notes, as all IVF doctors affirm, that most twin pregnancies will have a good outcome, and the intention is not to scare those who already have embarked on a twin pregnancy.

However he fails to comment on the conclusions of the study he quotes from Helmerholst:

With a twin pregnancy they may be relatively advantaged compared with other twin gestations, but this is poor consolation for the much greater risks of twin pregnancy overall. Virtually all perinatal and infant morbidity occurs more frequently in twins than in singletons.

Any obstetrician will confirm that twins can have huge obstetric complication risks: 2-3x of preeclampsia, and post partum haemorrhage, even after using Gleicher’s hypothetical correction factor, and 5-7x the chances of being born prematurely. Extreme prematurity is accompanied by a significant increased risk of cerebral palsy and that is not an intended outcome for any parent or their child. His assertion that women want two children and that some even want triplets attests to the general ignorance of these risks.

It also does not deal at all with increased late losses of multiple pregnancy. The saddest outcomes that we see in practice are those twin pregnancies where women go into very premature labour or lose both babies at around 25 weeks or less. The disappointment and grieving that accompanies this loss is profound and cannot be calculated in dollars or pounds.

When one looks at studies of families who have had twin or triplet pregnancies they have significant stresses, even to the extent that some have given their babies up for adoption because they are unable to cope. It is not reasonable to equate two single-spaced pregnancies with twins; being up all night with newly born twins, the doubling of the initial outlay costs, and the significant stresses of bringing up two toddlers are all material. Added to this, in the older age mother, as acknowledged by Dr. Gleicher, a significant number may request prenatal diagnosis to avoid age-related genetic abnormalities. In twin pregnancies the risks of the procedure are much increased, and dealing with the outcome is more complicated.

Because of the emotional stress of infertility, most prospective parents under-estimate the difficulties of raising multiple children, even if they are all healthy.  Understandably this stress is further intensified if one or both of the children are affected by any of the complications which commonly surround premature births.  Furthermore, if babies are affected by any of these complications, the stresses may last a lifetime rather than be limited to the period surrounding delivery.   This is not to mention the financial cost to the parents, and to healthcare systems involved in caring for the mother during a complicated pregnancy and the children whether in the short or long term after birth.

We should also not forget that Dr. Gleicher speaks as someone who lives and works in the USA, where there is little if no public funding for both fertility treatment and the consequences of multiple births which may last a lifetime.

Whatever the hypothesis, which may be interesting for doctors to mull over and discuss, there are significant risks to multiple pregnancies, and we should not be generating them deliberately. IVF babies also deserve the best start in life.

Professor Joep Geraedts
ESHRE Chairman

Dr. Francoise Shenfield
Member of ESHRE Task Force for Ethics and Law, Member Executive Committee

Professor Peter Braude
UK representative, ESHRE Committee of National Representatives

Statement from Dr Mark Hamilton and Rachel Cutting, Multiple Birth National Strategy Group.

"His report should be taken with caution. Evidence proves twin pregnancies are of greater risk than a single pregnancy. It is misleading, as he has done, to combine the risks of two single live births which are two independent events, each with a lower risk than that of a twin pregnancy.

With singleton pregnancies, the chance of having a stillborn baby, or one that dies soon after, is about five per 1,000. In a twin pregnancy it's four to five times that. If your first singleton pregnancy was uncomplicated, your chance of a problem the second time round is even lower, probably less than one in a thousand. Multiple pregnancies unquestionably expose mothers and babies to increased hazards.

The overwhelming evidence is that with appropriately selected patients, the chance of a livebirth is no different if you put back all the embryos available, one at a time. In some patients putting back more than one embryo at a time can expose both mother and potential child to avoidable hazards. Clinics throughout the UK are working towards the consistent practice of single embryo transfer in appropriately selected patients."

Dr Mark Hamilton, Chair of the British Fertility Society Dr Rachel Cutting, Executive Committee of the Association of Clinical Embryologists