Multiple births currently account for approximately 3% of all live births. In recent years, fertility treatments and the fact that women are having babies later has made multiple births more common.

Twins and triplets are more likely to be born early and need special care after birth than single babies. At UCLH we have a dedicated multidisciplinary team (MDT) that offers individualised care for pregnant women and their families, when expecting twins, triplets or more. We are a regional and national referral centre for multiple pregnancy complications such as twin to twin transfusion syndrome (TTTS). We strive to provide the highest standard of care and information in a calm and supportive environment.

Please note - for multiple pregnancies we can not accept any referrals after 28 weeks of pregnancy.

The number of tests and scans you’ll be offered will depend on the type of twins or triplets you're having. We will carefully monitor your pregnancy and assess the type of twins that you are carrying. You will be offered an ultrasound scan from 11 weeks 0 days to 13 weeks 6 days, and it's important to attend this appointment.

It is important to find out the 'chorionicity' of your pregnancy, which means whether your babies share a placenta (the afterbirth). Finding this out early is important because babies who share a placenta have a higher risk of health problems.

At 16 weeks you will be seen in the obstetric specialist multiple pregnancy clinic. The plan of your antenatal care and delivery will be discussed and your team will talk to you about the risks associated with multiple pregnancies.

You will then be seen in the midwifery-led multiple pregnancy clinic at 20, 24, 28, 30 and 34 weeks. You should attend the obstetric specialist multiple pregnancy clinic at 32 weeks to discuss the type and timing of your delivery.

It is important to attend all your appointments, so any problems can be picked up early and treated if necessary.

There are two types of twins according to the number of placentas:

  • dichorionic diamniotic (DCDA) twins – each has their own separate placenta with its own separate amniotic sac. With DCDA twins it is like two separate pregnancies happening at the same time.
  • monochorionic (MC) twins – there are two types of MC twins. Twins will share a single placenta with two separate amniotic sacs (MCDA) or they will share the same amniotic sac (MCMA).

All non-identical twins are DCDA, and one-third of identical twins are DCDA. The other two-thirds of identical twins are MCDA, and just 1% of identical twins are MCMA. The percentages of identical and non-identical twins born in the UK aren't routinely recorded, but according to the Multiple Births Foundation about one-third of twins are identical.

If your babies are MCDA, you can expect more scans and monitoring. The purpose of monitoring is to identify as early as possible any signs of concern such as twin to twin transfusion syndrome (TTTS) in MCDA pregnancies.

TTTS is a condition that affects MC twins. The common placenta may be shared unequally by the twins and one twin may have a share too small to provide the necessary nutrients to grow normally. The other twin may have a very big share which results in an overload with blood that could lead to cardiac failure and also causes this baby to have too much amniotic fluid (polyhydramnios).

If your twins are found to have TTTS you will be offered a treatment called laser ablation. During this procedure, vessels that are found to communicate between the twins are then coagulated using a laser beam.

If you are carrying MCMA twins you will also have frequent scans. With this type of twins there is often some cord entanglement, so delivery is recommended at 32 to 33 weeks gestation.

If your babies are DCDA twins they are not at risk of TTTS so we would scan your babies every four weeks.