1. Max Brinsmead MB BS PhD May 2015
Multiple Pregnancy
Max Brinsmead MB BS PhD
May 2015

2. Incidence of Multiple Pregnancy
Twins 1:80 in Caucasians
Assisted conception (IVF) explains most of the increasing incidence
But incidence is also affected by:
Race (1:50 Black Africans, 1:150 in Asians)
Family history (mean FSH levels)
Older maternal age
Increasing parity
Spontaneous triplets 1:6400 (Hellin’s Law)

3. Why are Multiples a Problem?
Prematurity
Risk of pre term delivery twins increased 5-fold
And 10-fold for triplets
14% twins and 41% triplets born very pre-term
Intrauterine growth restriction
Often manifest as discordant growth
Congenital malformations increased 2-fold
In monochorionic twins only
Increased rate of maternal pregnancy disorders
e.g. Pre eclampsia, gest. Diabetes, APH etc
Overall PN mortality increased 2 – 3-fold

4. But the single most important predictor of Risk in a twin pregnancy
Is Chorionicity

5. Types of twin pregnancy
Dizygotic – arise from two eggs.
These are non-identical twins
Monozygotic – one egg or embryo that splits
These are identical twins (clones)
But from a clinical perspective it is chorionicity that is important
Dichorionic (two chorion, separate sacs and placentas)
Monochorionic (one chorion and a shared placenta)
Monochorionic and diamniotic (separate sacs)
Monochorionic and monamniotic (only 1%)
About 1/3 twin pregnancies are monochorionic

6. Early Diagnosis is Important
The early diagnosis of twins is one of the reasons to advocate universal 1st trimester scans
There are implications for prenatal screening for aneuploidy
AND
It is the best time to document chorionicity
By looking for and studying the gestational sac(s)
“Y” sign = dichorionic
“T” sign = monochorionic
If in doubt refer for specialist scanning before 14 weeks

7. Monochorionic Twin Problems
Almost all monochorionic twins share vessels in their common placenta
But for 10 – 15% unidirectional flow results in twin-to-twin transfusion (TTS) which can:
Cause discordant growth
Has cardiovascular , haematological and amniotic fluid burdens
Result in the death of one twin
And a high risk of neurological damage to the survivor
MC and MA twins
Are at high risk of cord entanglement
Or succumb to acute polyhydramnios in the 2nd trimester

8. Management of Twin Pregnancy
Patient counselling
Issues of prenatal diagnosis
Nutrition and rest
More frequent AN visits
Dealing with the discomforts of pregnancy
Place of delivery
Timing of delivery
Mode of delivery
Rearing twins
A role for Support Groups

9. Management of Twin Pregnancy
Scan MC twins every 2 – 3 weekly from 16w
Best outcomes from TTS occur if it is diagnosed <24 wks
Refer to a Perinatal Centre
IUFD of one twin also requires Perinatal Centre review
Scan MC twins at 22w for cardiac defects
Scan DC twins at 28, 34 and 36w
or as clinically indicated
Add Doppler flow studies of umbilical artery
Cervical length monitoring?
Low threshold for admission
But routine “bed rest” long abandoned

10. When to Deliver? NICE Recommendations:
35 completed weeks for monochorionic twins
37 completed weeks for dichorionic twins
The ANZ RCT of elective IOL at 37 weeks vs standard care
235 women in multiple centres
Stopped early through lack of funding
Fewer SGA infants from IOL (RR = 0.39, CI 0.20 – and a trend towards fewer adverse infant outcomes (death, serious trauma, seizures, NICU admission >4 days etc)
Because of the very poor prognosis associated with MCMA pregnancies many perinatologists recommend:
El CS at 32w after steroids

11. Management of Twin Labour
Elective CS for a leading twin breech
A role for epidural anaesthesia (but not mandatory)
IV line. Group and save
Continuous monitoring if there is any other complication e.g. premature or discordant
Second twin requires presence of an obstetrician & someone capable of neonatal resuscitation
Take steps to deliver 2nd twin within 20 – 40 min
PPH prophylaxis
Consider thromboprophylaxis

12. Any Questions or Comments?
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