Multiple Pregnancy


  • Spontaneous twins occur in 1 in 80 pregnancies
    • Spontaneous triplets occur in 1 in 10000 pregnancies
  • The incidence is higher in pregnancy by infertility treatments


  • Chorionicity- refers to the membrane patterns
    • e.g. mono/dichorionic (sharing/independent palcentas)
    • e.g. mono/diamniotic (sharing/independent amniotic sacs)
  • Zygoticity-referes to the genetic profile (i.e. how many eggs)
    • e.g. monozygotic (identical twins) vs dizygotic (non-identical twins)

NB Monochorionic/monozygotic twins are at a much higher risk of complications than di-/di- twins


  • Usually at 12 week scan
  • May already have exaggerated pregnancy symptoms e.g. hyperemesis gravidarum; large for dates uterus
  • High AFP (alpha fetoprotein- found in yolk sac)
  • Clinicall examination: >1 foetal poles felt


  • Higher perinatal mortality/morbidity due to
    • congenital abnormalities; pre-term labour; growth restriction; pre-eclampsia; antepartum haemorrhage; twin to twin transfusion


See also NICE Guidelines (NICE quick reference guide to multiple pregnancy (management))

  • More frequent antenatal visits
  • More frequent scans
    • Detailed anomaly scan at 18 weeks
    • Regular scans from 28 weeks
  • Routine iron supplements
  • Delivery
    • >2 babies needs to be delivered by caesarian section
    • For twins, if one is presenting cephalic (L/ROA)- aim for vaginal delivery (still 50% will require caesarian)
    • Epidural

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