Multiple pregnancy

What is a multiple pregnancy?

A multiple pregnancy is a pregnancy that involves the development of more than one foetus in the womb, resulting from the fertilisation of two or more ovules. Children who are the result of a multiple pregnancy can be identical twins (sharing the exact same set of genes) or non-identical twins (born from two eggs released at the same time).

The rate at which identical twins occur is the same across the world, but the rate of non-identical twins varies from country to country, according to the age and ethnicity of the mother. In the UK, 16 in 1,000 births involve multiple pregnancy , 98 per cent of which are twins.

What are the symptoms of a multiple pregnancy?

The symptoms that distinguish a multiple pregnancy from a normal pregnancy include:

• more intense morning sickness and vomiting
• extreme drowsiness and fatigue
• rapid weight gain (5 kg in the first trimester, compared to 2-3 kg in a normal pregnancy)
• larger expansion of the uterus
• earlier sensation of foetal movement (two weeks before normal pregnancy)

What are the causes of a multiple pregnancy?

The main factors related to multiple pregnancy are:

• a family history of multiple pregnancy
• previous multiple pregnancy
• getting pregnant later in life
• ethnicity, with multiple pregnancy more common in women of West African ancestry

Fertility treatment in the form of IVF is associated with a higher likelihood of multiple pregnancy – with 24 per cent of successful IVF procedures resulting in multiple pregnancy.

What is the treatment for a multiple pregnancy?

Treatment is based on a more controlled consultation throughout pregnancy since it is a type of pregnancy that carries more risks than normal. This check-up may involve:

• a greater focus on nutrition including iron supplementation and folic acid
• more frequent consultations and scanning
• screening for conditions such as Down’s syndrome
• referral to a perinatologist (maternal-foetal specialist) to coordinate the follow-up
• tocolytic drugs (if a premature birth occurs)
• medications with corticosteroids (to help the lungs of foetuses mature)
• the choice to have an elective birth after 35-37 weeks

What are the risks and complications of a multiple pregnancy?

Multiple pregnancy carries the greater risk of a range of complications including:

• anaemia
• miscarriage
• haemorrhage
• pre-eclampsia
• stillbirth
• preterm birth
• congenital abnormalities