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Multiple Pregnancy

What is a multiple pregnancy?

Expecting two or more babies at one time is termed as multiple pregnancy. The ratio is one in eighty pregnancies and the chances of such pregnancies are increased by fertility treatments.

What are the different kinds of multiple pregnancies?

It is necessary for you to confirm the ‘chronicity’ of your pregnancy once you have found out about a multiple pregnancy after the early ultrasound scan. This is helpful in identifying if the babies are sharing the same placenta. It is also important to find out if the babies share the same placenta because such babies have a higher risk of complications.

Twins can be:

  • dichorionic diamniotic (DCDA) – if one egg splits after fertilisation or two different eggs are being fertilised. Each baby has a separate placenta, a separate outer membrane called ‘chorion’, and a separate amniotic sac.
  • monochorionic diamniotic (MCDA) – in case the fertilised egg splits later on, the babies share the same placenta but the amniotic sac and chorion are separate. Such babies are identical.
  • monochorionic monoamniotic (MCMA) – the least common case is when the babies share the same placenta, chorion, and the amniotic sac after the fertilised egg splits. Such babies are always identical. This is rare and sounds cute but has additional risks. In the same way, triplets can be trichorionic (each baby with separate placenta, amniotic sac, and chorion), dichronionic (two of the three babies share a placenta and a chorion and the third baby is separate), or monochorionic (all three babies share a placenta and chorion). Your babies are ‘monozygotic’ or identical if they share a placenta. Babies not sharing the placenta are ‘dizygotic’ or non-identical. But there is a possibility that babies not sharing a placenta maybe identical too.

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 because nearly a third of monozygotic or identical twins will each have their own placenta and hence will appear same on ultrasound scans as the DCDA (non-identical or dizygotic) twins.

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

Generally, women with multiple pregnancies are likely to have low risks and healthy babies. But multiple pregnancy requires greater care otherwise they will turn out to have more risks. Ultrasound scans are increased in number to reduce these risks to you and the babies.

The common minor problems that most pregnant women face are increased and more common in multiple pregnancies such as morning sickness, heartburn, swollen ankles, varicose veins, backache and gets better after delivery. Problems that occur in pregnancy are more common with twins and include:

  • Anaemia – developing babies require a lot of iron which turns into anaemia.
  • Pre-eclampsia – in this condition, protein amount is increased in urine and high blood pressure.

For further information, see the RCOG patient information Pre-eclampsia ( 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;
  • A higher chance of needing a caesarean section or assisted vaginal delivery to deliver your babies. 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 before 37 weeks have increased risks of problems, mainly breathing, feeding, and infection.

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 ( 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)

Blood supply is the same in case of twins sharing the same placenta (monochorionic pregnancies). In about 15 of 100 such pregnancies, an unbalanced blood flow may be detected. This condition is twin-to-twin syndrome (TTTS).

The ‘donor’ baby receives little blood and has a low blood pressure while the other baby or ‘recipient,’ receives excessive blood and has high blood pressure.  Frequent TTS scans will be performed. It can either be mild with no treatment required or it may be serious where you will be offered to be treated in the hospital with experts.

What extra care will I need during pregnancy?

A specialist team will be responsible for taking care of you and you will be advised to have your babies in a consultant-led maternity unit with a neonatal unit. The specialist team will have an obstetrician and a midwife who has specialised in multiple pregnancies. You will need more antenatal clinical visits at your hospital in case of multiple pregnancies. Extra ultrasounds for a closer look at your babies’ growth will be offered.

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

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

You will be offered a scan after 12-14 weeks to screen for chromosomal conditions like Down’s syndrome like every other pregnant woman. Blood tests that are taken at the same time can be combined with the scan results so that any chromosomal risks can be detected, even in multiple pregnancies.

To look at your baby’s development, you will be offered a scan after 20 weeks as well. These tests have higher chance of indicating any risks in cases with single baby pregnancy. If there are any issues, your consultant will be able to give you advices.


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