Multiple pregnancy happens in about one in 60 pregnancies. Most women with a multiple pregnancy will have a healthy pregnancy and will give birth to healthy babies, however complications are more common. You will be offered extra antenatal checks and ultrasound scans to make sure that you are well and to monitor your babies closely. If you have a multiple pregnancy, you are more likely to give birth to your babies prematurely. You will be advised to give birth in hospital. 

Twins or triplets can be identical (monozygotic) or non-identical (di/tri-zygotic). Identical twins or triplets have come from one egg, which has been fertilised by one sperm and has then split into two (or three) after fertilisation. Identical twins or triplets share identical genes, will look the same and be the same sex. Non-identical twins or triplets have come from different eggs, which have been fertilised by different sperm. If your babies are non-identical, they will have different genes and will be no more similar than any other brothers or sisters. 

Chorionicity refers to whether your babies each have their own placenta or whether they share a placenta. If your babies share a placenta (monochorionic) they are always identical. If they each have their own placenta (dichorionic/trichorionic) they are more likely to be non-identical but can still be identical.

Twins can be:

• Dichorionic Diamniotic (DCDA) – This means each baby has its own placenta and its
  own sac. This is the most common type of twin pregnancy.
• Monochorionic Diamniotic (MCDA) – This means the babies share a placenta but they
  are each in their own sacs.
• Monochorionic Monoamniotic (MCMA) – This means that both babies share a placenta
  and are within the same sac. This is a much rarer type of twin pregnancy.

You are more likely than someone having a single baby to experience more serious problems during your pregnancy. This may include:

Anaemia – this is usually caused by a shortage of iron because your developing babies
use up a lot of iron. You will be offered regular blood tests to check whether you are
becoming anaemic and you will be offered treatment with tablets if your iron levels are
low.

Pre-eclampsia this is a condition that causes high blood pressure and protein in
your urine during pregnancy. Your blood pressure and urine will be checked regularly
and, depending on your other risk factors, you may be advised to take aspirin tablets
to reduce your chance of developing this.

A higher chance of needing a caesarean birth or an assisted vaginal birth (forceps or ventouse) – your healthcare team will support you to create a birth plan and you should discuss your choices and preferences with your team.

Post-partum haemorrhage this means that you may bleed more than average after
you have given birth. You will be offered medications at birth to reduce the chance
of this happening.

Prematurity
Overall, around 8 in 100 babies (8%) are born prematurely (before 37 weeks). This is more
common if you have a multiple pregnancy and can either be because you go into labour early or because your healthcare team recommend that the babies are born early.

If you are pregnant with twins you have a 60 in 100 (60%) chance of going into labour and giving birth before 37 weeks of pregnancy.

If you are pregnant with triplets you have a 75 in 100 (75%) chance of going into labour and
giving birth before 35 weeks. Babies born prematurely have an increased chance of health problems, particularly with breathing, feeding and infection. The earlier your babies are born, the more likely this is to be the case. Depending on how early they have been born, they might need to spend time in the neonatal unit. Wherever possible your babies will be kept together however depending on their individual needs they may need to be cared for separately.

Problems with growth
Having a multiple pregnancy increases the chance that your placenta may not work as well as it should. This can affect the babies’ growth and wellbeing during the pregnancy. Sometimes both babies may be small but more often only one baby is small. If only one baby is affected this is called selective fetal growth restriction (S-FGR). You will be offered extra ultrasound scans during your pregnancy to check for growth problems:

• If you are having DCDA twins you will be offered scans at least every 4 weeks from 24
  weeks.
• If you are having MCDA or MCMA twins you will be offered scans at least every 2
  weeks from 16 weeks.
• If you are having triplets or more you will be offered growth scans depending on your
  specific circumstances.

Twin-to-twin transfusion syndrome (TTTS)
Babies who share a placenta (monochorionic pregnancies) also share the blood supply from the placenta. In around 15 in 100 (15%) monochorionic pregnancies, the blood flow to the babies may be unbalanced. This is called twin-to-twin transfusion syndrome (TTTS). Triplet pregnancies can also be affected by this. One baby, the ‘donor’, receives too little blood while the other baby, the ‘recipient’, receives too much blood. 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. You will be monitored with frequent scans for signs of TTTS. If you notice any of the following you should contact your healthcare professional immediately: sudden abdominal pain and/or swelling sudden breathlessness change in the babies’ movements.

When to deliver?

Your health care team should start to discuss your birth plan with you from around 24 weeks. Your decision as to whether to plan for a vaginal birth (usually after an induction of labour) or a caesarean birth will depend on several factors including the position in which the babies are lying in your uterus (womb), how well the babies are growing and your personal preferences about the birth.

• Around 37 weeks of pregnancy if you are having DCDA twins
• Around 36 weeks if you are having MCDA twins
• Around 32–34 weeks if you are having MCMA twins
• Around 35 weeks if you are having triplets

Hope you found this information helpful.