Multiple pregnancy

What causes multiple pregnancy?

1 in every 60 births in the UK are twins, triplets or more. You are more likely to carry multiple babies if:

• you got pregnant using IVF (if you had more than 1 embryo transferred into your womb)
• you are over the age of 35, when you’re more likely to release more than 1 egg during ovulation
• you have a family history of non-identical twins.

Identical twins usually do not run in families. 

When will I find out if I’m having more than 1 baby?

Your first ultrasound scan at 10-14 weeks will usually show if you’re having more than 1 baby. If you’re having IVF, you will have earlier scans and may find out before this.

What types of multiple pregnancies are there?

The ultrasound scan will show whether your babies share a placenta and/or amniotic sac. This will affect your care during pregnancy and birth.

Types of twins

• Dichorionic diamniotic twins (DCDA) – each baby has a separate placenta and amniotic sac.
• Monochorionic diamniotic twins (MCDA) – the babies share a placenta but have separate amniotic sacs.
• Monochorionic monoamniotic twins (MCMA) – the babies share a placenta and amniotic sac.  

Types of triplets

• Trichorionic triamniotic triplets – each baby has a separate placenta and amniotic sac.
• Dichorionic triamniotic triplets – 1 baby has a separate placenta and 2 of the babies share a placenta. All 3 babies have separate amniotic sacs.
• Dichorionic diamniotic triplets – 1 baby has a separate placenta and amniotic sac, and 2 of the babies share a placenta and amniotic sac. 

Will my babies be identical?

Identical twins or triplets come from a single egg that has been fertilised by 1 sperm before splitting into 2 or 3.  

Non-identical twins or triplets come from separate eggs that have been fertilised by different sperm.  

If your babies share a placenta, it means they are identical. If they do not share a placenta, they are more likely to be non-identical but may be identical.

The most accurate way to tell if twins are identical is through a DNA test. This can only be done after your babies are born.

Possible complications of multiple pregnancy

Most women and birthing partners carrying twins, triplets or more will go on to have healthy pregnancies and healthy babies.

In any pregnancy, there are possible complications to be aware of. If you are having multiple babies, you may be more likely to get some of these. Your maternity team will offer you extra scans and tests to check that you and your babies are well and to pick up any problems early on.

There’s lots of support available from your maternity team and organisations, such as the Twins Trust. 

Stronger pregnancy symptoms

You may have stronger pregnancy symptoms if you are having a multiple pregnancy. This is because of the increase in pregnancy hormones. For example, you may be more likely to have morning sickness and increased tenderness in your breasts.  

As your pregnancy progresses, you may get other symptoms, such as:

• ankle swelling
• varicose veins in the legs and vulva (the external female sex organs)
• backache
• tiredness.

Every pregnancy is different, so you may not have any or all of these symptoms. Remember that your team is there to help you, so talk to your midwife or doctor if you have any concerns.

Anaemia

If you are carrying more than 1 baby, you are at higher risk of developing anaemia. Your midwife will give you the same advice as other pregnant women about having a healthy, balanced diet and what vitamins (supplements) to take during pregnancy.  

You will be offered a blood test to check for anaemia at your booking appointment, at 20-24 weeks and at 28 weeks of pregnancy. Tell your GP or midwife if you think you have any anaemia symptoms.

Pre-eclampsia  

Pre-eclampsia is a condition that only affects pregnant women and birthing people. It is a combination of raised blood pressure (hypertension) and protein in your urine (proteinuria). If you are having more than 1 baby 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. Talk to your healthcare professional about whether low-dose aspirin will help you.

Intrahepatic cholestasis of pregnancy (ICP)  

Intrahepatic cholestasis of pregnancy (ICP) is a liver problem that develops during pregnancy. It can be serious, especially if you’re expecting more than 1 baby. The main symptom is itching without a rash. Find out more about ICP.

Blood clots

Deep vein thrombosis (DVT) is a serious condition where a blood clot forms in a deep vein in the body, usually in the leg. DVT is not common in pregnancy or in the first 6 weeks after birth, occurring in only 1-2 of every 1000 women and birthing people.

The risk of developing DVT during pregnancy is higher however if you are carrying multiple babies.

Call 111 or arrange an urgent appointment with your GP or midwife if you have these symptoms in your leg:

• pain, swelling or tenderness in 1 leg, usually in the calf
• warm skin or a heavy ache in the affected area
• red or darkened skin in the affected area (This may not be obvious on black and brown skin).

Complications in labour

You may be more likely to need help with labour and birth if you are having a multiple pregnancy. For example, you may be offered:

• an induction of labour
• a caesarean section  
• an assisted birth.  

You are more likely to bleed more heavily than usual after birth, but you may be offered medicine to reduce this chance. Your doctors and midwives will support you and explain what is happening during labour and birth. You will also have a chance to talk to your team about your birth plan a few weeks before you are due to have your babies.

Problems with your baby's growth

If you’re having twins or more, this increases the chance of the placenta not working as well as it should. This can affect the babies’ growth and development.

Most twin, triplet or more babies will be slightly different in size, but sometimes 1 baby is much smaller than the other/s. This is called selective fetal growth restriction.  

You will be offered extra scans during pregnancy to check how your babies are growing.

Twins Trust has more information about complications such as growth restriction.

Premature birth

Your maternity team will advise you to give birth before your due date. This is safer for your babies.  

You may go into premature labour naturally or you may choose to have an induction of labour or a caesarean section. Most mothers go into labour naturally – this happens in 60 out of 100 twin pregnancies and 75 out of 100 triplet pregnancies. You are more likely to give birth early if you have given birth early before. Find out more about causes of premature birth.

Your babies may need to be cared for in the neonatal unit if they’re born very early. You can read more about how your premature babies will be cared for in hospital.

You may be offered a medicine called a corticosteroid during pregnancy. This helps your babies’ lungs develop before the birth.

Twin-to-twin transfusion syndrome (TTTS)  

Babies sharing a placenta (monochorionic pregnancies) also share the same blood supply. In around 15 in 100 monochorionic pregnancies, the blood flow may be unbalanced. This means that 1 baby receives too little blood and has a low blood pressure, while the other baby receives too much blood and has a high blood pressure. This is called twin-to-twin transfusion syndrome (TTTS) but it can also affect triplet pregnancies.

You will be monitored with frequent scans for signs of TTTS. It can be mild and may not need any treatment. If it’s more serious, you will be offered treatment in a hospital that specialises in treating TTTS.

It’s important to be aware of the symptoms of TTTS, which may include:

• sudden pain or swelling in your tummy
• suddenly feeling out of breath
• changes in your babies’ movements.

Contact your midwife or maternity unit straight away if you have any of these symptoms or if you are worried.

Twins Trust has more information about TTTS.

Baby loss

Most multiple pregnancies progress well, but multiple pregnancies do have a higher chance of ending in loss. This may be due to complications such as chromosome abnormalities, complications of having a shared placenta such as TTTS, or selective fetal growth restriction. Complications linked to premature birth may also increase the risk. This can be extremely difficult. If your other baby or babies are born healthy this may cause some very complicated feelings.  

Tommy’s is here to help. We have information and support for anyone who has experienced the loss of a baby. You can talk to a Tommy’s midwife for free, Monday-Friday, 9am-5pm. You can call them on 0800 0147 800 or email [email protected]. You can also join the Tommy’s Support Group on Facebook.  

Twins Trust also run a bereavement service.

What will my antenatal care be like?

Specialist care

It’s recommended that you have care from a specialist team of doctors and midwives who are experts in managing twin and triplet pregnancies. You will have a plan for your care during pregnancy and birth, which will include extra scans and antenatal appointments.

This team can also include support from other health professionals. For example, you may see a mental health professional, a physiotherapist, an infant feeding specialist or a dietitian for advice about:

• antenatal and postnatal mental health and wellbeing
• eating well in pregnancy
• possible complications of multiple births
• your birth choices
• feeding your babies
• parenting.

The advice for keeping healthy in pregnancy is similar whether you're expecting twins, triplets or just 1 baby. Eating a healthy, balanced diet, doing regular exercise and drinking lots of fluid will help.  

Twins Trust has developed a care pathway that describes the extra care you should be offered from the time of your first hospital scan, as well as the routine care that is offered to all women during pregnancy.  

More antenatal appointments

The number of extra appointments you have will depend on: 

• how many babies you’re carrying
• whether they share a placenta or amniotic sac
• whether there are any complications.

You will also have extra ultrasound scans to check how your babies are growing and pick up any problems as early as possible.

If you are having twins

If you are having an uncomplicated twin pregnancy where the babies each have their own placenta (dichorionic diamniotic), you will have at least 8 antenatal appointments. At least 2 of these will be with a specialist doctor (obstetrician). You will also be offered ultrasound scans about every 4 weeks from 20 weeks of pregnancy.

If you are having an uncomplicated twin pregnancy where the babies share a placenta (monochorionic diamniotic), your pregnancy will be monitored more closely. You will have at least 11 antenatal appointments, 2 of which should be with an obstetrician. You will be offered scans every 2 weeks from 16 weeks of pregnancy.

If you’re having triplets

If you are having an uncomplicated triplet pregnancy where each baby has their own placenta (trichorionic triamniotic), you will have at least 9 antenatal appointments. At least 2 of these should be with a specialist doctor (obstetrician). You will also be offered ultrasound scans every 2 weeks from 24 weeks of pregnancy.

If any of your babies share a placenta (dichorionic triamniotic or monochorionic triamniotic), your pregnancy will be monitored more closely. You will have at least 11 antenatal appointments, 5 of which should be with an obstetrician. You will also be offered a scan every 2 weeks from 16 weeks of pregnancy.

If you are having twins or triplets that share an amniotic sac

If any of your babies share an amniotic sac, you will be offered extra care and monitoring, as well as a plan for your individual care. This may be in a specialist fetal medical centre.  

If you have complications in pregnancy

If you or your babies have any complications during pregnancy, you will have an individual care plan. This may include extra scans or appointments.

Can I still have screening for Down’s syndrome and other conditions?

You will be offered the usual pregnancy scan at 11–14 weeks to screen for health conditions such as Down's syndrome, Edwards' syndrome and Patau's syndrome. This is the same for all pregnancies, whether you’re expecting 1 baby, twins or more.

Some screening tests are not recommended in multiple pregnancies and some results can be less accurate. If a test shows a higher chance of a health condition, it can be difficult to know which baby may be affected. Your healthcare team will give you information and support to help you make decisions about screening. 

If you are pregnant with triplets and the test results show a higher chance of Down’s, Edwards’ or Patau’s syndrome, you will be referred to a specialist fetal medicine unit.

You will also be offered a scan at about 20 weeks to check how your babies are growing.

Getting more support

You can contact the Twins Trust on their Twinline, 0800 138 0509. This free, confidential service is offered between 10am and 1pm and again at 7pm until 10pm, Monday to Friday.

Our midwives are available to answer any questions you might have or even just to chat if you need to talk about the tests you will have. Our support line is open Monday-Friday, 9am-5pm – call us on 0800 014 7800. Or you can email [email protected]

The charity Antenatal Results and Choices offers support and information about antenatal testing. You can contact their helpline by phone on 020 7713 7486 or by emailing [email protected]