Multiple Pregnancy Flashcards
What is the incidence of twins?
1/105
What is the incidence of triplets?
1/10,000
What does dizygotic mean?
Non identical
Develop from 2 separate ova that were fertilised at the same time
What monozygotic twins mean?
Identical twins
Develop from a single ovum which has divided to form 2 embryos
Is dizygotic or monozygotic more common?
80 = dizygotic
What are monoamniotic twins?
Twins that share the same amniotic sac
Always identical
Always monochorionic - share the same placenta, but have 2 separate umbilical cords
Monoamniotic monozygotic twins are associated with…
Increased spontaneous miscarriage, perinatal mortality rate
Increased malformations, IUGR, prematurity
Twin to twin transfusions
The more the twins share, the higher the risk
The incidence of dizygotic twins is increasing, mainly due to…
Infertility treatment
What predisposing factors are there for twins?
Previous twins FH of twins (dizygotic only) Increased maternal age Induced ovulation and IVF Race - Afro Caribbean especially Nigerian Yoruba women Multigravida
What pregnancy features are associated with twins?
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
What antenatal complications can occur?
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
What fetal complications can occur?
Perinatal mortality 5x higher than singleton
Prematurity = main problem - 60% before 37w
Growth restriction
Malformation rates higher, especially monozygotic
What is the mean gestation for twins?
37 w
For triplets: 33w
What complications can occur in labour?
PPH increased
Malpresentation is common
Cord prolapse
Uterus has more to contract, so increased risk of atony
How is it managed?
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)
What precautions at labour should be made?
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
What is twin to twin transfusion syndrome?
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
Multiple pregnancies in the same sac are managed…
By consultants at tertiary centres - very high risk
Is screening for genetic conditions more or less reliable in multiple pregnancy?
Less reliable as HCG and AFP raised anyway
Vaginal or elective CS is fine for both DCDA or MCDA twins, but what is advised for MCMA?
Advise CS - increased risk of TTTS especially at time of delivery
Why is epidural recommended?
Stabilising second twin can be painful
