Established in SA Oct. 1992

Some of the Reasons for Twin Loss


Important Note: This section offers only basic information about some of the reasons for loss in a multiple pregnancy.

It is not meant to replace professional medical advice.


Further enquiries should be directed to either the contact groups listed on the ‘links’ page of this site, or your own family doctor. This information is published in the brochure ‘Some of the Reasons for Twin Loss’ by National Twin Loss Support. © 2009. Please note that websites listed in the reference section may have moved since the information was originally quoted.


Reason: Vanishing Twin Syndrome

This occurs early during a pregnancy when one twin seems to ‘disappear’ as a result of spontaneous abortion. Fetal tissue is then ‘absorbed by the other twin, the placenta, or the mother, thus giving the appearance that the twin “vanished”’. (Parenting of Multiples, Jan. 2004. The syndrome is diagnosed using ultrasound. The first scan will reveal two babies in the womb and the subsequent visit will only show one. This of course can be extremely distressing for the parents, but is often treated with indifference by many medical personnel, family and friends. Accurate and credible information regarding Vanishing Twin Syndrome in the past, has been difficult to find. Thankfully due to increased attention being paid to this condition, the resulting broader research, has now rectified this problem.


Parenting of Multiples, Jan. 2004, (online). Available: [Accessed 30 Mar. 2005].

Other Useful Sites:

Twin Loss NZ:



Reason: Twin to Twin Transfusion Syndrome

 This is a disease of the placenta that ‘affects identical twin pregnancies’. (The Twin to Twin Transfusion Syndrome Foundation, 2004). The common placenta may contain abnormal blood vessels ‘which connect the umbilical cords and circulation of the twins’ (The Twin to Twin Transfusion Syndrome Foundation, 2004), or ‘the common placenta may also be shared unequally by the twins’. (The Twin to Twin Transfusion Syndrome Foundation, 2004). This results in one twin receiving too many necessary nutrients for survival and the other, too few. Although Twin to Twin Transfusion Syndrome can appear at any time during the pregnancy, Chronic TTTS usually appears in the early stages, whilst acute TTTS may occur during the latter stages, including delivery. Chronic cases have relatively poor outcomes because the babies have not had enough time to develop properly in the womb. Acute cases have a higher survival rate but a greater chance of disabilities.


The Twin to Twin Transfusion Syndrome Foundation, 2004, (online). Available:

[Accessed 30 Mar. 2005].

Other Useful Sites:

Australian Twin To Twin Transfusion

Syndrome  Support Group


Reason: Conjoined Twins

This occurs in approximately every 4 out of 400,000 births. Survival rates are low with one or both twins eventually dying. The majority of  conjoined twins who do survive will either be  severely handicapped or have an extremely reduced life span. Most conjoined twins are female and the majority are stillborn. Surgical separation is extremely risky and   success rates depend greatly upon where the babies are joined. Babies joined at the rear of the head, on the side, at the pelvis, or at the abdomen have the highest chance of survival, although many complications such as brain damage for example may occur as a result of separation. Babies joined at the front of the head and chest, often sharing organs such as the heart, have not been known to survive. ‘Up until 1990, surgical separation of conjoined twins has been attempted 167 times … the babies that survive are truly miracle babies!’ (CTI, date unknown).



CTI, date unknown, Conjoined Twins Int. Facts, (online). Available: [Accessed 30 Mar. 2005].


Reason: Multifetal Pregnancy Reduction


 This is an extremely controversial  medical procedure. ‘Reduction ... is usually performed between the 10th and 12th weeks of pregnancy by injecting one or more of the fetuses.’ (Haddon, L. P., date unknown). IVF and fertility drugs have resulted in a much higher multiple pregnancy rate. Multifetal pregnancy reduction is  sometimes considered the best course of action to increase the chances of a viable pregnancy. ‘The timeframe for multifetal reduction … is often very narrow, sometimes as short as only 3 or 4 days’ (Haddon, L. P., date unknown), thus placing parents under greater stress and pressure when deciding whether to use this course of treatment. Mostly used in the United States, particularly during the early days of InVitro-Fertilization (IVF) when success rates were much lower, many medical professionals now question the ethics of this procedure. ‘Pregnancy loss subsequent to fetal reduction has been reported as ranging from 1 to 40%’ (Lipitz, S., 1999).



Haddon, L. P., date unknown, Multifetal Pregnancy Reduction, (online). Available: [Accessed 3 Apr. 2005].


Lipitz, S., 1999, The First World congress on: Controversies in Obstetrics, Gynecology &    Infertility, Prague, Czech Republic, (online). Available: [Accessed 30 Mar. 2005].


Reason: Twin Reversed Arterial Perfusion Sequence (TRAP)

 A non hereditary condition occurring in approx. 1% of identical twin pregnancies. One twin lacks a functioning cardiac system and therefore receives blood from the normally developing twin, called the “Pump Twin”. This places enormous demands upon the Pump Twin’s heart, risking cardiac failure if left untreated. Surgery can be carried out in the latter stages of pregnancy and success rates of up to 95% have been achieved in the United States in recent years.



Philadelphia Children’s Hospital, Centre for Fetal Diagnosis (online). Available: [Accessed 21 March 2007].


back to index

Copyright © 2009 National Twin Loss Support. All rights reserved.