Multiple Pregnancy

Question 1

What is the incidence of twins?

Answer 1

1/105

Question 2

What is the incidence of triplets?

Answer 2

1/10,000

Question 3

What does dizygotic mean?

Answer 3

Non identical

Develop from 2 separate ova that were fertilised at the same time

Question 4

What monozygotic twins mean?

Answer 4

Identical twins

Develop from a single ovum which has divided to form 2 embryos

Question 5

Is dizygotic or monozygotic more common?

Answer 5

80 = dizygotic

Question 6

What are monoamniotic twins?

Answer 6

Twins that share the same amniotic sac
Always identical
Always monochorionic - share the same placenta, but have 2 separate umbilical cords

Question 7

Monoamniotic monozygotic twins are associated with…

Answer 7

Increased spontaneous miscarriage, perinatal mortality rate
Increased malformations, IUGR, prematurity
Twin to twin transfusions

The more the twins share, the higher the risk

Question 8

The incidence of dizygotic twins is increasing, mainly due to…

Answer 8

Infertility treatment

Question 9

What predisposing factors are there for twins?

Answer 9

Previous twins
FH of twins (dizygotic only)
Increased maternal age 
Induced ovulation and IVF 
Race - Afro Caribbean especially Nigerian Yoruba women 
Multigravida

Question 10

What pregnancy features are associated with twins?

Answer 10

Early features:
Uterus large for dates
Hyperemesis
Later there may be polyhydramnios

Signs: > 2 poles felt, multiplicity of fetal parts felt, 2 fetal heart rates heard (reliable if rates differ by > 10 beats/min)
US confirms diagnosis

Question 11

What antenatal complications can occur?

Answer 11

Polyhydramnios
Pregnancy induced HTN, pre-eclampsia more common
Anaemia commoner - increased iron and folate requirements
Antepartum haemorrhage incidence rises - from both abruption and placenta praevia (large placenta)
Gestational diabetes

Question 12

What fetal complications can occur?

Answer 12

Perinatal mortality 5x higher than singleton
Prematurity = main problem - 60% before 37w
Growth restriction
Malformation rates higher, especially monozygotic

Question 13

What is the mean gestation for twins?

Answer 13

37 w

For triplets: 33w

Question 14

What complications can occur in labour?

Answer 14

PPH increased
Malpresentation is common
Cord prolapse
Uterus has more to contract, so increased risk of atony

Question 15

How is it managed?

Answer 15

US at 11-14 weeks for viability, chorionicity, amnioticity, nuchal translucency, malformations

DCDA -dating scan every 4 weeks from 24-26
MCDA -dating scan every 2 weeks from 16-34

Check FBC at 20-24w
Give aspirin >12w if other risks for pre-eclampsia
More antenatal visits - weekly from 30w
Offer elective at 37w for uncomplicated dichorionic twins, 36w plus steroids for uncomplicated monochorionic twins
(Most women spontaneously deliver before these dates)

Question 16

What precautions at labour should be made?

Answer 16

2 obstetricians present
IV access
Anaesthetist available are delivery
Paediatricians one per baby at delivery in case resuscitation needed - 2nd twin has higher chance of asphyxia

Question 17

What is twin to twin transfusion syndrome?

Answer 17

It can effect monochorionic identical multiples
Abnormal blood connections form in the placenta and allow blood to flow unevenly between babies
One twin called the donor, becomes dehydrated and the other, called the recipient, develops high BP and produces too much urine

Question 18

Multiple pregnancies in the same sac are managed…

Answer 18

By consultants at tertiary centres - very high risk

Question 19

Is screening for genetic conditions more or less reliable in multiple pregnancy?

Answer 19

Less reliable as HCG and AFP raised anyway

Question 20

Vaginal or elective CS is fine for both DCDA or MCDA twins, but what is advised for MCMA?

Answer 20

Advise CS - increased risk of TTTS especially at time of delivery

Question 21

Why is epidural recommended?

Answer 21

Stabilising second twin can be painful