1. Multiple
pregnancies
Sarah and Tim

2. Epidemiology and risk factors
Occurs in 1-2% of pregnancies. 98% of these are twins.
Incidence is increasing.
Risk factors:
•Assisted reproduction e.g. IVF (20%), ovulation induction
(5-10%)
•Increasing maternal age
•High parity
•Afro-Caribbean origin
•Maternal family history
However, the incidence of monozygotic twins remains fairly
stable regardless of risk factors.

3. Classification
•Number of foetuses
•Number of fertilised eggs (zygosity)
•Number of placentae (chorionicity)
•Number of amniotic cavities (amnionicity)

4. Diagnosis
• Symptoms
-Increased vomiting in early pregnancy
-Symptoms of associated diseases
• Signs
-Early palpable uterus
-“Large for dates”
-2 or more palpable foetal poles
-Signs of associated diseases

5. Diagnosis
Prenatal USS at 11-13w
-To confirm, monitor growth, determine chorionicity
-Assign nomenclature to babies
-Use largest baby for gestational age
T sign (monochorionic diamniotic) Lamda sign (monochorionic
monoamniotic)

6. Differential diagnosis
Other causes of ‘large for dates’:
• Polyhydramnios
• Fibroids
• Urinary retention
• Ovarian mass

7. General management
•USS at 10-13w to assess viability, chorionicity, major
congenital malformtion, nuchal translucency (aneuploidy,
TTTS)
•After 20w, USS every <28d. If >25% difference in size or
IUGR then tertiary referral
•Elective delivery at 35w (triplets), 36w (monochorionic) or
37w (dichorionic)
•If vaginal delivery then continuous intrapartum monitoring,
availability of c-section and experienced obstetrician
•Maternal education/support, early recognition of
psychological disturbance

10. Complications- Maternal
• Gestational Diabetes
• Hyperemesis
• Preeclampsia
• Anaemia
• Antepartum Haemorrhage
• Increased complications caused by non
obstetric conditions (e.g. cardiac issues)

11. Complications- Foetus
Miscarriage/severe preterm delivery
-50% are preterm
-In dichorionic twins, later miscarriage in 2%, very
preterm in 5% (12% and 10% for monochorionic twins)
Perinatal mortality
Foetal abnormalities
-x2 increased risk for dichorionic (x4 in monochorionic)
-Selective foeticide is possible but may cause death in
remaining twin (5-10%)
-Avoid procedure in fatal abnormalities unless threatens
survival of normal twin
Chromosomal defects

12. Death of one twin
•Associated with poor outcome depending on classification
and gestation
-Worse after midgestation
-Dichorionic- onset of labour, no change
-Monochorionic- 25% have complications e.g. brain
damage, death. Due to shift in hemodynamic volume.
•Risk of maternal complications
-e.g. DIC, pre-eclampsia
Foetus papyraceus

13. Twin-to-twin transfusion syndrome
•Imbalance in blood flow across the
anastomoses in monochoronic twins
-Causes hypoxia/hypovolaemia in
one foetus resulting in IUGR and
oligiouria
-And vice versa in the other
•Apparent at 18-24w
-Increase in abdominal girth,
discomfort, confirm with USS
•90% end in miscarriage or very
preterm delivery
•Amniocentesis or foetoscopic guided
laser coagulation

15. Complications- Intrapartum
• Malpresentation
• PPH (10%)
• Premature separation of the
placenta/abruption
• Entanglement of the cord
• Cord prolapse
• Tetanic uterine contraction
• Foetal Distress

16. Thank you!