About this information

Finding out you are having twins, triplets or even quadruplets can be exciting, but it may also bring worries and concerns for you, your partner and family members. If you are expecting more than one baby, it is important that you are well prepared for the changes that will take place both during your pregnancy and after the babies’ birth.

This information is for you if you know you are carrying more than one baby. It tells you about:

• the different types of multiple pregnancy
• what it means for you and your babies
• the care you will receive while you are pregnant
• the options for birth so that you can make an informed choice.

This leaflet provides an overview of multiple pregnancy: it focuses mainly on twins but it is relevant to any pregnancy where more than one baby is expected. Further information and support is available from your midwife and obstetrician and from the multiple-pregnancy organisations listed at the end of the leaflet.

What is a multiple pregnancy?

A ‘multiple pregnancy’ is the term used when you are expecting two or more babies at the same time. It occurs in about one in 80 pregnancies. Fertility treatment increases the chances of multiple pregnancy.

What are the different kinds of multiple pregnancy?

At your early ultrasound scan which confirms whether you are carrying twins or triplets, it is important to find out the ‘chorionicity’ of your pregnancy. This is to help identify whether your babies share a placenta and it is important because babies who share a placenta have a higher risk of complications.

Twins can be:

• • dichorionic diamniotic (DCDA) – if two eggs are fertilised or if one egg splits soon after fertilisation, each baby has its own placenta with its own outer membrane called a ‘chorion’ and its own amniotic sac
• • monochorionic diamniotic (MCDA) – if the fertilised egg splits a little later, the babies share a placenta and chorion but they each have their own amniotic sac; these babies are always identical
• • monochorionic monoamniotic (MCMA) – much less commonly, the fertilised egg splits later still and the babies share the placenta and chorion and are inside the same amniotic sac; these babies are always identical; this is rare and carries additional risks.

Similarly, triplets can be trichorionic (each baby has a separate placenta and chorion), dichorionic (two of the three babies share a placenta and chorion and the third baby is separate), or monochorionic (all three babies share a placenta and chorion).

If your babies share a placenta, they are identical or ‘monozygotic’. Most babies who do not share a placenta are non-identical or ‘dizygotic’. However, it is possible for babies not sharing a placenta to be identical as well. This is because nearly a third of monozygotic or identical twins will each have their own placenta and hence will have the same appearance on ultrasound scans as the DCDA (non-identical or dizygotic) twins.

What does a multiple pregnancy mean for my babies and me?

Most women who have a multiple pregnancy have healthy pregnancies and healthy babies. However, complications are more common in multiple pregnancy and having extra care during your pregnancy including more ultrasound scans reduces these risks to you and your babies.

For you

Minor problems that many pregnant women experience, such as morning sickness, heartburn, swollen ankles, varicose veins, backache and tiredness, are more common in multiple pregnancies. They get better naturally after the babies are born.

Any problems that arise in any pregnancy are more common with twins and include:

• anaemia – this is usually caused by a shortage of iron because developing babies use up a lot of iron
• pre-eclampsia – a condition that causes high blood pressure and protein in your urine; for further information, see the RCOG patient information Pre-eclampsia (www.rcog.org.uk/en/patients/patient-leaflets/pre-eclampsia)
• a higher chance of bleeding more heavily than normal after the birth – doctors and midwives are trained to deal with these situations; for more information, see the RCOG patient information Heavy bleeding after birth (postpartum haemorrhage) (www.rcog.org.uk/en/patients/patient-leaflets/ heavy-bleeding-after-birth-postpartum-haemorrhage)
• a higher chance of needing a caesarean section or assisted vaginal delivery to deliver your babies.

For your babies

Prematurity

You are more likely to have your babies early if you are expecting twins or triplets:

• • about 60 in 100 sets of twins will be born spontaneously before 37 weeks of pregnancy
• • about 75 in 100 sets of triplets will be born spontaneously before 35 weeks
• • in comparison, only about 10 in 100 women who are pregnant with one baby will give birth before 37 weeks.

Babies born earlier than 37 weeks of pregnancy have an increased risk of problems, particularly with breathing, feeding and infection. The earlier your babies are born, the more likely this is to be the case. They may need to be looked after in a neonatal unit. You will be supported to spend as much time as you can with them and you will be encouraged to breastfeed. For more information, see the RCOG patient information Premature labour (www.rcog.org.uk/en/patients/patient-leaflets/premature-labour).

Having a baby born early can be worrying and distressing for parents. Your babies are more likely to need special care after birth. Your doctor or midwife will be happy to talk to you about this and can give you information about support groups that you might find helpful.

Problems with growth

Having twins increases the chance of the placenta not working as well as it should. This can affect the babies’ growth and wellbeing.

Twin-to-twin transfusion syndrome (TTTS)

Twins sharing a placenta (monochorionic pregnancies) also share the blood supply. In around 15 in 100 monochorionic twin pregnancies, the blood flow may be unbalanced. We call this twin-to-twin transfusion syndrome (TTTS). One baby, the ‘donor’, receives too little blood and has a low blood pressure while the other baby, the ‘recipient’, receives too much blood and has a high blood pressure. You will be monitored with frequent scans for signs of TTTS. It can be mild and may not require any treatment, or it can be serious, in which case you will be offered treatment in a hospital with specialist expertise.

What extra care will I need during pregnancy?

You will be under the care of a specialist healthcare team and will be advised to have your babies in a consultant-led maternity unit that has a neonatal unit. Your team will usually include an obstetrician and a midwife who specialises in multiple pregnancies.

Having a multiple pregnancy means that you will need more visits to the antenatal clinic at your hospital. You will be offered extra ultrasound scans to monitor your babies’ growth more closely.

• For twin pregnancies where the babies each have their own placenta (dichorionic), this will mean having an ultrasound scan about every 4 weeks.
• If your babies share a placenta (monochorionic), your pregnancy will be monitored more closely, with scans offered every 2 weeks from 16 weeks of pregnancy onwards.
• You may be advised to take iron tablets and folic acid each day throughout your pregnancy.
• If you are having twins and have any other risk factors for pre-eclampsia, you may be advised to take low-dose aspirin from 12 weeks of pregnancy onwards to reduce the risk.

Can I still have screening for Down syndrome and other abnormalities?

Like all women, you will be offered a scan at about 12–14 weeks to screen for chromosomal conditions such as Down syndrome. Even in multiple pregnancies, blood tests taken at the same time can be combined with the scan results to assess the risk of one or both of your babies having a chromosome problem; for further information, refer to the UK National Screening Committee (www.gov.uk/topic/ population-screening-programmes/fetal-anomaly).

You will also be offered another scan at around 20 weeks to look at your babies’ development. The chance of these tests finding a problem is slightly higher than if you were pregnant with only one baby. Your specialist team will be able to offer you advice if the screening shows any problems with your pregnancy.

Key points

• Multiple pregnancy occurs in about one in 80 pregnancies.
• While most women with multiple pregnancies will have a healthy pregnancy and healthy babies, complications are more common.
• Extra antenatal checks and ultrasound scans to monitor your babies will be offered.
• You are more likely to have your babies early if you have a multiple pregnancy.
• You will be advised to give birth in a consultant-led maternity unit.
• Your midwives and local support groups can provide you with advice and support after your babies are born.

Making a choice

Further information

Twins & Multiple Births Association (TAMBA): www.tamba.org.uk

The Multiple Births Foundation: www.multiplebirths.org.uk

National Institute for Health and Care Excellence (NICE): Multiple pregnancy: Antenatal care for twin and triplet pregnancies: www.nice.org.uk/guidance/cg129/informationforpublic

UK National Screening Committee: www.gov.uk/topic/population-screening-programmes/fetal-anomaly

Sources and acknowledgements

• This information has been developed by the RCOG Patient Information Committee. It is based on the NICE clinical guideline Multiple pregnancy: Antenatal care for twin and triplet pregnancies, which you can find online at: www.nice.org.uk/guidance/cg129, and the RCOG Green-top guideline Management of monochorionic twin pregnancy, which you can find online at: www.rcog.org.uk/guidelines-research-services/guidelines/gtg51. The guidelines contain full lists of the sources of evidence used.
• This leaflet was reviewed before publication by women attending clinics in Birmingham, Liverpool and Newcastle Upon Tyne, by the RCOG Women’s Network and by the RCOG Women’s Voices Involvement Panel.
• The RCOG produces guidelines as an educational aid to good clinical practice. They present recognised methods and techniques of clinical practice, based on published evidence, for consideration by obstetricians and gynaecologists and other relevant health professionals. This means that RCOG guidelines are unlike protocols or guidelines issued by employers, as they are not intended to be prescriptive directions defining a single course of management.