Risks to the child

What could be better than completing your family in one go, with twins or even more babies? After all, most of us know normal, healthy twins, or read the heart-warming newspaper stories of families who are delighted with their quads, quins, or even more babies, following IVF (in vitro fertilisation).

Sadly, this is not the whole picture – the reality is that for many twins and triplets, life can be fragile and difficult.

At present, about 1 in 4 IVF or ICSI (in vitro fertilisation or intra-cytoplasmic sperm injection) pregnancies leads to a multiple birth. This means that after IVF/ICSI, you are around 20 times more likely to have a multiple pregnancy than you would be if you’d conceived naturally.

Other fertility treatments, such as drugs and intrauterine insemination (IUI) can also increase the risk.

Why are twins and triplets at greater risk of problems?

The health risks for twins and triplets are greatly increased compared with those for singletons mostly because multiples tend to be born prematurely and underweight. The risk of early and late miscarriage is also higher for twins than for singleton pregnancies.

The chance of a single embryo dividing and resulting in identical twins is higher after IVF though it is not yet known why this happens. So it is possible to end up with identical twins from a single transferred embryo, or triplets from two embryos.

The majority of these identical babies share a placenta and are at even higher risk from complications during pregnancy than non-identical twins, such as twin-to-twin transfusion syndrome, which can cause serious health problems and death.

If a multiple pregnancy is thought to be a serious health threat to mother or babies, the clinician may suggest a fetal reduction. This involves aborting one or more of the fetuses.

Premature birth – the facts

Many twins and triplets are born prematurely, meaning that these babies are born before the normal time for healthy singleton babies:

• Singleton babies are usually carried for about 40 weeks and tend to have normal birth weights.
• At least half of twins are born before 37 weeks and with low birth weights, making them at high risk of serious health problems and death. Many are born before 35 weeks, when they often need neonatal care. Their birth weight is around 800–1000g less than singletons.
• Over 90% of triplets are born before 37 weeks and many are born so early that they have a greater risk of long-lasting, serious health problems or may die soon after birth.

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What are the common problems with premature births?

Prematurity can cause many problems and may even result in the death of the baby. The problems caused by prematurity can range from those that, although serious, affect only the early stages of the child’s life, to those that have a devastating and lifelong impact.

Early stage problems

• Between 40–60% of IVF twins need to be transferred to the intensive care unit when they are born. Only 20% of singleton IVF babies need the same level of care.
• 8% of twins need help with their breathing and 6% suffer from respiratory distress syndrome (breathing difficulties) compared with 1.5% and 0.8% for singletons respectively.
• The overall risk of death during birth or the first year of life is higher for twins than for singletons.
• The risk of death around the time of birth is 3-6 times higher for twins and 9 times higher for triplets. A recent study estimated that if all IVF babies born in the UK had been singletons, the deaths of 126 babies could have been avoided in 2003. 

Longer term problems

Problems that may affect twins and multiples after the early stages of life are:

• A small percentage of twins have severe health problems that will affect their entire lives (for example cerebral palsy, which affects between 4 and 6 times as many twins compared with singleton babies).
• Prematurity and low birth weight carry the risks of lower IQ and are linked with Attention Deficit Hyperactivity Disorder and long-lasting behavioural difficulties.
• Problems with language development is more common with twins. Twice as many twins need speech therapy compared with singletons.
• According to a Japanese study, in 7.4% of twin pregnancies, at least one child had a disability, such as cerebral palsy, impaired sight, or congenital heart disease.

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