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Multiple Pregnancy

From Mediwikis

Twins make up 1.5% of pregnancies. This figure is on the rise due to the prevalence of IVF. All pregnancy changes are exaggerated in multiple gestations, so expect more, and more severe complaints.

Risk Factors

  • IVF
  • Raised age
  • African
  • Family history of fecundity
  • High Parity

Note that monochorionic ≠ Monozygotic, and Dichorionic ≠ Diamniotic. Depending on when splitting of ovum occurs, monozygotic twins may be mono or diamniotic.


  • Average Gestation = 37 weeks. Offer elective birth from 36+0 for monochorionic twin (after course of corticosteroids) and 37+0 for dichorionic twins. Continuing uncomplicated twin pregnancies beyond 38 weeks gestation increases the risk of foetal death.
  • Miscarriage risk higher in monochorionic than dichorionic twins
  • 25% chance on twin disappears before any scans.
  • Later loss of one twin is associated with poor outcomes for the remaining sibling.
  • IUGR
  • Congenital abnormality risk is individual, so unaffected by gestation.

Twin-Twin Transfusion Syndrome

Imbalance of arteriovenous anastamoses in monochorionic pregnancies (15%). One twin becomes overperfused, and the other underperfused.

  • Underperfusion→Oligovolaemia→IUGR, Oligohydramnios
  • Overperfusion→Polyvolaemia→Polyhydramnios, Heart Failure

Treat with amniocentesis of polyhydramniotic twin and laser ablation of anastamoses. Might need umbilical cord occlusion in worst case scenario.