Monochorionic triplets, which share a placenta, are very rare, and can be at risk of complications such as Twin to Twin Transfusion Syndrome (TTTS) and having significantly different growth patterns, which in turn leads to a higher risk of stillbirth. We need to conduct research to find out the safest way of managing this kind of pregnancy.

Twins anaemia polycythaemia sequence, or TAPS, is a condition which affects identical twins, causing one to become anaemic with low blood flow, and the other to have a very high blood flow. We don’t currently know what is the best treatment for TAPS and more research is needed to find out how we should treat babies diagnosed with TAPS.

Selective fetal growth restriction (sFGR) is a condition where one baby follows a typical growth pattern, while the other is much smaller than expected. This condition can affect both identical and non-identical babies. It carries a risk of stillbirth or very premature birth. More research is needed to make sure that doctors can differentiate growth restriction which needs treatment from a normal size difference between the babies, and know how best to look after babies with this condition.

There is currently not enough evidence to indicate whether a twin pregnancy will be delivered successfully by vaginal birth rather than C-section. Understanding how we can predict a successful vaginal birth will allow doctors to give women more accurate advice when agreeing their birth plan.

Similarly, in some pregnancies where the first baby is delivered vaginally, complications can mean that the second baby needs to be delivered by C-section. Being able to identify risk factors for the second baby and understand why this happens could allow doctors to support parents better when deciding on the best way for them to give birth.

Obstetric cholestasis is a condition which can lead to extremely premature birth or stillbirth, and is more likely to affect pregnancies with more than one baby compared to singleton pregnancies. However, not much is known about the effect of the condition in twin pregnancies and more research is needed to understand how it impacts them and how doctors should manage these pregnancies.

We don’t currently know enough about the effect of gestational diabetes in twin pregnancies compared to singleton pregnancies. This study will try to establish who is likely to develop gestational diabetes and what the impact might be on the pregnancy and the babies.

Twin babies do not follow the same growth patterns as singleton babies, and therefore their growth can’t be measured in the same way. Following on from the twin pregnancy growth charts, more data is needed to establish what is a typical weight for a twin baby at birth, and what is a low birthweight that requires intervention. This would prevent the over-diagnosis of growth restriction in twin babies at birth and ensure that appropriate treatment is given to those who truly need it.

Hypertensive disorders, which include pre-eclampsia, can be dangerous for both mother and babies. By doing research into how it affects a twin pregnancy, doctors can understand who might be at risk, what the effect is on the babies and how they can manage pregnancies which are at risk of or diagnosed with a hypertensive disorder.