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RCOG release: Early diagnosis and specialist care needed for twins who share the same placenta

News 16 November 2016

Updated guidelines for healthcare professionals could help save the lives of unborn babies by ensuring early diagnosis and identification of complications in monochorionic twin pregnancies.

A monochorionic pregnancy is a multiple pregnancy, most commonly a twin pregnancy, in which babies are dependent on a single, shared placenta. This type of pregnancy, affecting nearly a third of all twin pregnancies, can cause complications which require regular ultrasound screening, early diagnosis and specialist care, state the guidelines published today by the Royal College of Obstetricians and Gynaecologists (RCOG). New patient information about having a multiple pregnancy is also published today.

Due to recent advancements in assisted reproductive technology, as well as changes to the maternity population, including later maternal age, multiple pregnancies in the UK have doubled over the last 40 years. These factors have also increased the risk of monochorionic twinning.  

Mark Kilby, Professor of Fetal Medicine from the University of Birmingham and lead author of the RCOG guideline said:

“Monochorionic twin pregnancies are more complex and require close surveillance. Very sadly the risk of one or both of the twins dying is increased. Early diagnosis between 11-14 weeks gestation, alongside regular ultrasound screening every fortnight within a multidisplinary twin pregnancy clinic is therefore essential to identify and treat complications as quickly as possible.

“Using the latest scientific evidence this guideline provides healthcare professionals with best practice advice for caring for women and their babies. However, despite growing research in this area, there is still an urgent need for clearer evidence around less common complications of monochorionic twin pregnancies. This will inevitably help all twins get the best possible start to life.”

The guideline covers some of the complications that arise. Affecting 15% of monochorionic twin pregnancies, twin-to-twin transfusion syndrome (TTTS), where part of the blood flow is diverted from one twin to the other, leads to one twin suffering a reduced blood supply. This in turn leads to growth restriction, while the other twin’s heart will become strained as it works harder to cope with the extra blood supply. Without treatment 90% of babies are likely to die. Timely diagnosis and expert treatment significantly improves outcomes for the twins and this guideline recommends laser ablation[1] as the most effective treatment.

In addition, selective growth restriction (SGR), with a significant difference in size between the babies, can complicate up to 20% of these twin pregnancies. SGR is associated with an increased risk of perinatal death or the babies being born too small and too early. Depending on the severity of the growth restriction, treatment options vary, but can include early delivery. 

For the first time, this guideline provides advice for healthcare professionals on twin anaemia-polycythaemia sequence (TAPS), where one baby has a low haemoglobin (anaemia) and the other has a high haemoglobin (polycythaemia). Regular screening for this condition is essential for complicated monochorionic twin pregnancies; especially babies complicated by TTTS, even if treatment has been performed. However, the guideline highlights a lack of evidence for the routine surveillance of all monochorionic twins, the most appropriate treatment and data on short and long term outcomes. It calls for further research into the optimal management for this condition.

Keith Reed, Chief Executive of the Twins and Multiple Births Association, (Tamba), said:

“Although multiple births account for just 3% of all births in the UK, they account 7% of all stillbirths in England, Wales and Scotland in 2014. The risk of preterm birth is also higher for multiples, occurring in just over half of twin pregnancies and they are six times more likely to have cerebral palsy than a singleton baby[2]. These stark statistics highlight the urgent need to improve care for women expecting more than one baby.

“Receiving a diagnosis of monochorionicity can be worrying for parents, therefore healthcare professionals must be well-trained in providing clear and accurate information in a sensitive manner, as well as signposting to charities such as Tamba and The Multiple Births Foundation for additional support.”

Case studies:

Kirsty from Birmingham had a monochorionic pregnancy and her twins were diagnosed with TTTS:

“I was told at 18 weeks that my twins had severe twin-to-twin transfusion syndrome and the recipient twin had cardiac failure. It was a traumatic time for all of us when I underwent the laser ablation procedure, but thankfully both babies survived and I continued with my pregnancy. Each week, I received regular check-ups but at 31 weeks, an ultrasound scan noted that the larger baby was not growing so well and the decision was made that doctors should perform a caesarean section. Emily and Cassie were born at 32+2 weeks and remained in hospital for six weeks before being allowed home. Both are now thriving well at home with my husband and me. 

“Thankfully our babies were fine, but we do appreciate the risks involved with TTTS and how things could have been very different. That’s why we back anything that can be done to improve survival rates, which is hopefully something these guidelines can achieve.”

From London, Stacey’s twins were also diagnosed with TTTS at 16 weeks:

“After being monitored weekly, I found out at 16 weeks that my twins Abigail and Evelyn had a condition where one twin wasn’t receiving enough nourishment from the placenta. By 21 weeks the condition had become so bad, doctors told me the donor twin was likely to die. We decided that the best option was to try laser ablation surgery but sadly Abigail died that night. I went into premature labour at 29+2 weeks and delivered two tiny babies. The survivor, Evelyn, weighed just 700g and Abigail 300g. After 172 days in NICU, Evelyn was finally allowed home.”


For media enquiries and copies of the guideline, please contact the RCOG press office on 020 7772 6444 or email

For further information about additional case studies, please contact the Twins And Multiple Birth Association (Tamba) on 01252 332344 or 


This is an updated version of the Green-Top Guideline first published in 2008. If you would like a copy of the new guidelines please contact the press office.

New patient information ‘Multiple pregnancy’ is also published today.

The NICE guideline on the management of multiple pregnancies is available here.

The Royal College of Obstetricians and Gynaecologists is a medical charity that champions the provision of high quality women’s healthcare in the UK and beyond. It is dedicated to encouraging the study and advancing the science and practice of obstetrics and gynaecology. It does this through postgraduate medical education and training and the publication of clinical guidelines and reports on aspects of the specialty and service provision.

Tamba is the only UK-wide charity working to improve the lives of twins, triplets or more, and their families. This is done through campaigning to improve health and developmental outcomes; funding clinical research to reduce the risks faced before, during and after birth; and by providing practical support for all families, including those in crisis.

The Multiple Births Foundation, founded in 1988, is a national and international authority on multiple births and the only charity internationally which employs healthcare professionals dedicated to supporting multiple birth families and educating and advising professionals about their special needs.

[1]This procedure involves closing all of the abnormal connecting blood vessels between the twins, preventing the transfusion effect.