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Twin Pregnancy (1 of 4)
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Author: Zoe Adams
Role: Doctor
Date written: April 2013
Review date: May 2016
Version: 1.0
Code: PI1054
Congratulations on your twin pregnancy!
Discovering that you have a twin pregnancy can be quite a surprise. Our
leaflet for you aims to answer common questions you might have and
give some idea of what to expect during your pregnancy. It contains
information about:
• Identical and non-identical twins
• Antenatal care
• Labour and delivery
• Postnatal support.
How common are multiple pregnancies?
16 women per 1000 in 2009 had multiple births. The incidence of twin
pregnancies is increasing due to the increased number of couples
undergoing fertility treatment.
When are multiple pregnancies diagnosed?
Twin pregnancies are usually diagnosed on the first ultrasound (or
dating) scan at 10-14 weeks. At this point we also determine the type
of twin pregnancy that you have, based on the number of placentas.
A specific care plan will be made for you at your booking appointment
dependent on the type. (The placenta is the organ that connects the
baby to the lining of your womb and supplies your baby with nutrients
and blood).
What are the types of twin pregnancy?
• Twins sharing a placenta (monochorionic): are usually identical
twins. This occurs when one fertilized egg splits into two. Your
babies are the same sex and share a placenta but will usually
have individual sacs of fluid surrounding them. We call this
monochorionic diamniotic and it will be recorded in your notes as
MCDA. If your babies share both their placenta and their sac of
fluid we call this monochorionic monoamniotic (MCMA).
• Twins with separate placentas (dichorionic): are more common
and usually non-identical. Non-identical twins occur when two
eggs are fertilized by two individual sperm. Your babies might
be the same or different sex. Each baby has a separate placenta
and separate sac of surrounding fluid. This will be recorded in
your notes as dichorionic diamniotic (DCDA). Occasionally a
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Salisbury District Hospital, Salisbury, Wiltshire SP2 8BJ
www.salisbury.nhs.uk
Twin Pregnancy (2 of 4)
single fertilized egg can split into two at an early stage, this results in identical twins with
separate placentas. This type of pregnancy would also be noted as dichorionic diamniotic.
What are the problems associated with twin pregnancies?
Minor problems such as morning sickness, heart burn, ankle swelling, varicose veins and
tiredness are more frequent.
More significant problems more common in twin pregnancies include:
• Anaemia (low red blood count)
• Hypertension (high blood pressure)
• Pre-eclampsia (high blood pressure and protein in your urine)
• Gestational diabetes (pregnancy associated diabetes)
• Antepartum and postpartum haemorrhage (bleeding during pregnancy and following
delivery)
• Growth restriction (either one or both babies are small)
• Operative delivery (use of a suction cup or forceps, caesarean section)
• Postnatal illness (including postnatal depression)
• Twin-twin transfusion syndrome (see explanation below)
• Pre-term delivery
Twin-Twin Transfusion Syndrome (TTTS)
This is a condition related to sharing of a single placenta and is therefore specific to
monochorionic twin pregnancies. It is known to complicate 10-15% of twins.
When the babies share a placenta there is a risk that they do not share it equally and therefore
one twin will receive more blood flow and nutrients than the other. The connecting blood vessels
mean that blood can be transfused from one twin (the donor) to the other (the recipient). The
recipient twin becomes overloaded with blood, this puts extra strain on the heart and increases
urine production which results in excess amniotic fluid. The donor twin loses blood volume and
therefore does not produce as much urine and thus amniotic fluid. This can result in impaired
growth, anaemia and in the worst cases some twins do not survive.
We assess for TTTS by repeated ultrasound scans that assess the placenta, the size of the
babies and the amount of amniotic fluid surrounding them. Once a monochorionic pregnancy
is diagnosed you will be scanned every two weeks. If you are diagnosed with TTTS you will
be managed at our regional fetal medicine centre where they will be able to best discuss the
possible treatment options.
If we tell you that you have a monochorionic pregnancy and you begin to experience any of the
following symptoms you should seek advice from your midwife or obstetrician immediately:
• sudden increase in abdominal size
• breathlessness.
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Salisbury District Hospital, Salisbury, Wiltshire SP2 8BJ
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Twin Pregnancy (3 of 4)
How will I be supported in my pregnancy?
We like to closely monitor you during your pregnancy and give you information and support
throughout.
Antenatal Care
You will have a multidisciplinary team consisting of an obstetrician, ultrasonographers,
community midwife and your GP. Your appointments at the hospital and in the community are an
opportunity to discuss: nutrition, antenatal mental health and wellbeing, signs and symptoms of
pre-term labour, the likely mode and timing of delivery, and breastfeeding.
Your blood pressure and urine will be checked at each appointment.
You will have more frequent ultrasound scans than in a single pregnancy and these scans are
likely to start earlier. You will be able to choose a dating scan or a Trisomy 21 (Down’s Syndrome)
screening scan at 12 weeks. A more detailed scan at approximately 20 weeks will look at the
major physical structures of your babies. We use the frequent scans to monitor the growth of
your babies.
You will be offered a blood test at 20-24 weeks to identify if you require early supplementation
with iron or folic acid. This will be checked again at 28 weeks. You may be offered iron or folic
acid supplements
You may be advised to take aspirin 75mg daily from 12 weeks until the birth of your babies if:
• this is your first pregnancy,
• you are 40 years of age or older,
• you have had a gap in your pregnancies of more than 10 years,
• you have a BMI ≥35kg/m2 at first visit or
• a family history of pre-eclampsia.
Your community midwife will discuss your birth plan with you and explore all the likely options.
This will be around 32-34 weeks gestation.
Labour and delivery
We advise that you deliver your babies in hospital where there is better access to experienced
people and resources. Decisions related to timing and the way in which you will deliver are best
discussed with your obstetrician and relate to the type of twin pregnancy you have.
We know that twin pregnancies are more likely to require intervention during delivery however
this does not exclude a vaginal delivery. If twin 1 is head down then we would support trying for
a vaginal delivery. It is important to realise that if we are unable to deliver your babies vaginally or
if there are causes for concern we would need to deliver them by caesarean section.
Pain relief options, including gas & air, local injection and epidurals will be discussed with you
when you reach the labour ward.
60% of women with twin pregnancies deliver spontaneously before 37 weeks. We recommend
that you have a bag packed ready to come into hospital from 34 weeks. If we need to deliver
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Salisbury District Hospital, Salisbury, Wiltshire SP2 8BJ
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Twin Pregnancy (4 of 4)
your babies early or we are concerned about pre-term labour you will be offered steroid
injections to help to mature your babies’ lungs.
Spontaneous pre-term birth and elective pre-term birth are associated with an increased risk
of your babies requiring admission to the special care baby unit. If we are concerned that you
are going to deliver early and our special care baby unit is full, we may have to transfer you to a
regional hospital. We will try transfer you back to us as soon as possible.
Signs of pre-term labour
• loss of fluid from the vagina
• regular tightenings
• abdominal pain.
If you experience any of these symptoms before 37 weeks please contact your midwife or labour
ward for advice.
Postnatal care
It is extremely tiring having one baby and even more so with two. Your midwife and GP will be
able to help support you in the postnatal period along with your family and friends.
Postnatal depression is more common with twin pregnancy.
It is possible to breast feed twins and our breast feeding co-ordinator will be on hand to
support you with this if you wish to do so.
Where can I find more information?
Please ask questions when you see your midwife or obstetrician at your clinic appointment. If
you have an emergency or any signs of pre-term labour or TTTS you can contact us on:
• switch board: 01722 336262
• labour ward directly: 01722 425183
We run antenatal classes specifically for twin pregnancies four times a year. These classes are
held in the Old Antenatal Clinic, 10am - 3pm by Midwives Monica Edmonds and Natasha Nelmes
– please ask your midwife or contact Maternity Day Assessment (01722 425185) for details of the
next class.
Salisbury Twins and More Club meet every second Monday at the Impact Centre, Salisbury and
you are very welcome to attend antenatally. Please contact Susan Bradley (01980 610356) for
further information.
Homestart provide help following delivery and can be contacted at 6, Salisbury Street,
Amesbury.
The following websites have useful information for women expecting twins, including leaflets on
TTTS:
TAMBA – Twins and Multiple Births Association www.tamba.org.uk
Multiple Births Foundation www.multiplebirths.org.uk
Labour Ward
01722 425183
© Salisbury NHS Foundation Trust
Salisbury District Hospital, Salisbury, Wiltshire SP2 8BJ
www.salisbury.nhs.uk