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National Collaborating Centre for Women's and Children's Health (UK). Multiple Pregnancy: The Management of Twin and Triplet Pregnancies in the Antenatal Period. London: RCOG Press; 2011 Sep. (NICE Clinical Guidelines, No. 129.)

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Multiple Pregnancy: The Management of Twin and Triplet Pregnancies in the Antenatal Period.

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2.1. Multiple pregnancy

The incidence of multiple births has risen in the last 30 years. In 2009, 16 women per 1000 giving birth in England and Wales had multiple births compared with 10 per 1000 in 1980.* In total, 10,855 multiple births were recorded in 2008, of which 10,680 were twin births and 171 were triplet births. This rising multiple birth rate is due mainly to increasing use of assisted reproduction techniques, including in vitro fertilisation (IVF). Up to 24% of successful IVF procedures result in multiple pregnancies. Increasing maternal age at conception and changes in population demographics (due to immigration) have also contributed to the rise. Multiple births currently account for 3% of live births.§

Multiple pregnancy is associated with higher risks for the mother and babies. Women with multiple pregnancies have an increased risk of miscarriage, anaemia, hypertensive disorders, haemorrhage, operative delivery and postnatal illness.** The risk of pre-eclampsia for women with twin pregnancies is almost three times that for singleton pregnancies, while the risk for triplet pregnancies is increased nine-fold.†† In general, maternal mortality associated with multiple births is 2.5 times that for singleton births.‡‡ Women with multiple pregnancies are also more likely to have more marked symptoms of minor ailments of pregnancy (such as nausea and vomiting) than women with singleton pregnancies.

The overall stillbirth rate in multiple pregnancies is higher than in singleton pregnancies: in 2009 the stillbirth rate was 12.3 per 1,000 twin births and 31.1 per 1,000 triplet and higher-order multiple births, compared with 5 per 1,000 singleton births.1;2§§

The risk of preterm birth is also considerably higher in multiple pregnancies than in singleton pregnancies, occurring in 50% of twin pregnancies (10% of twin births take place before 32 weeks of gestation).3–6 Duration of pregnancy becomes shorter with increasing numbers of fetuses. The higher incidence of preterm birth in multiple pregnancies is associated with an increased risk of neonatal mortality and long-term morbidity (especially neurodevelopmental disability and chronic lung disease).*** Prematurity accounts for 65% of neonatal deaths among multiple births, compared with 43% in singleton births. ††† The significantly higher preterm delivery rates in twin and triplet pregnancies mean there is increased demand for specialist neonatal resources.

Risks to the babies depend partly on the chorionicity and amniocity of the pregnancy.7–11 Monochorionic twins share a placenta and have interconnected circulations, while dichorionic twins have separate placentas. Different combinations of shared and separate placentas occur in triplet pregnancies and other higher-order multiple pregnancies: monochorionic triplets share a single placenta; trichorionic triplets each have separate placentas; and dichorionic triplets occur when two fetuses share a placenta and the other has a separate placenta. Some risks to babies of multiple pregnancies are associated particularly with shared placentas. One condition associated with a shared placenta is feto-fetal transfusion syndrome (FFTS), which most commonly occurs in twin pregnancies (where it is termed twin-to-twin transfusion syndrome; TTTS). However, FFTS may also occur in monochorionic and dichorionic triplet pregnancies. FFTS affects 15% of monochorionic pregnancies and accounts for about 20% of stillbirths in multiple pregnancies. It is also associated with a significantly increased risk of neurodevelopmental morbidity. Additional complications can arise in monoamniotic pregnancies, in which two or more fetuses share a placenta and an amniotic sac. Although such pregnancies are very rare (1–2% of monochorionic pregnancies are monoamniotic), they are at risk of umbilical cord entanglement because there is no membrane separating the fetuses.9–11

Additional risks to the babies include intrauterine growth restriction (IUGR) and congenital abnormalities. In multiple pregnancies, 66% of unexplained stillbirths are associated with a birthweight of less than the tenth centile, compared with 39% for singleton births. Major congenital abnormalities are 4.9% more common in multiple pregnancies than in singleton pregnancies.12

Because of the increased risk of complications, women with multiple pregnancies need more monitoring and increased contact with healthcare professionals during their pregnancy than women with singleton pregnancies, and this will impact on National Health Service (NHS) resources. An awareness of the increased risks may also have a significant psychosocial and economic impact on women and their families because this might increase anxiety in the women, resulting in an increased need for psychological support.

There is considerable variation in the provision of antenatal care for women with multiple pregnancies in England and Wales. A survey in 200813 reported that limited expertise was focused on multiple births across the NHS. It also reported a lack of access to education about multiple pregnancy for healthcare professionals and inadequate continuity of antenatal care. This could have an impact on pregnancy outcomes. ‘Antenatal care’ (NICE clinical guideline 62)14 did not cover the management of multiple pregnancies. There is therefore a need for high-quality, evidence-based guidance on the organisation and delivery of antenatal care for women with multiple pregnancies.

This guideline contains recommendations specific to twin and triplet pregnancies and covers the following clinical areas:

  • optimal methods to determine gestational age and chorionicity
  • maternal and fetal screening programmes to identify structural abnormalities, chromosomal abnormalities and FFTS, and to detect IUGR
  • the effectiveness of interventions to prevent spontaneous preterm birth
  • routine (elective) antenatal corticosteroid prophylaxis for reducing perinatal morbidity.

The guideline also advises how to give accurate, relevant and useful information to women with twin and triplet pregnancies and their families, and how best to support them.

2.2. For whom is this guideline intended

This guideline is of relevance to those who work in or use the NHS in England, Wales and Northern Ireland, in particular:

  • healthcare professionals involved in the care of women with twin and triplet pregnancies (including general practitioners [GPs], midwives, obstetricians and ultrasonographers)
  • those responsible for commissioning and planning healthcare services, including primary care trust commissioners, Health Commission Wales commissioners, and public health and trust managers
  • women with twin and triplet pregnancies and their families.

A version of this guideline for women with twin and triplet pregnancies and the public is available from the NICE website (

2.3. Related NICE guidance

This guideline is intended to complement other existing and proposed works of relevance, including the following guidance published by NICE:



See Table 2 in Characteristics of birth 2 2009: 09/11/10 (366Kb - Xls) and table 1 in Characteristics of Mother 1 2009: 21/10/10 (251Kb - Xls)

Copyright © 2011, National Collaborating Centre for Women’s and Children’s Health.

No part of this publication may be reproduced, stored or transmitted in any form or by any means, without the prior written permission of the publisher or, in the case of reprographic reproduction, in accordance with the terms of licences issued by the Copyright Licensing Agency in the UK []. Enquiries concerning reproduction outside the terms stated here should be sent to the publisher at the UK address printed on this page.

The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore for general use.

Bookshelf ID: NBK83098


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