- Multiple pregnancies are more common, with twins occurring in 1 in 73 pregnancies in the UK in 1995. Chorionicity affects pregnancy risks like fetal loss and cerebral palsy rates. - Twin-twin transfusion syndrome occurs in 25% of monochorionic twins and can have high mortality rates if severe. Fetoscopic laser ablation has better outcomes than serial amnioreduction. - There is controversy around optimal delivery methods for twins regarding vaginal delivery versus C-section and timing between twin deliveries. Factors like chorionicity, presentation, and growth need to be considered.

1. Multiple pregnancy for MRCOG

4. Prevalence death & cerebral palsy Western Australia 1980-1989

5. Fetal and Perinatal Mortality Fetal Loss (<24 weeks) Perinatal Loss (>24 weeks) Sebire N et al. BrJOG 1997 12.1% 1.8% 2.8% 1.6% Monochorionic Dichorionic

6. Presumed zygosity & cerebral palsy ( Western Austailia 1956-1985) P=0.0026 Concordant Discordant Monozygotic 6 9 Dizygotic 0 21

7. Chorionicity versus zygocity 0-4 days 4-7 days 7-14 days Fused or unfused

14. Diagnosis of chronic TTTS Monochorionic Stuck twin Polyhydramnios Growth discrepancy Doppler Hydrops PROGRESSIVE*

16. Fetoscopic Laser Ablation Ville et al. 1998 BrJOG DiLia 1998 (TTTS website) Non-selective Laser Ablation 202 cases 59% Survival 4% neurological handicap rate

18. FLA vs Amniodrainage n=116, 17-25 weeks’ gestation n=43: Amniodrainage, Bonn; n=73: Laser ablation, Hamburg Hecher K et al. 1999 AmJOG Overall survival (NS) 61% 51% FLA Abnormal brain scan (p <0.03) 6% 18% FLA FLA Amnion Drainage Gestation at delivery (p <0.02) 33.7 30.7

23. Single puncture amniocentesis Sebire et al 1996 Miscarriage risk 1-2% Selective fetocide 8%+ Sample one sac in MC Careful documentation

27. Conjoined twins

28. Acardiac twinning

30. Low birthweight a Singleton b Twins c Triplets d quads 52% twins (n=5416) <2500g compared 6% singletons ( Regan 2001)

31. Delivery of pre-term twins 37

32. Elective delivery of twins Sairam et al 2002

35. Presentations of twins FIRST TWIN SECOND TWIN Percentage of presentation combinations in labour Cephalic Breech Other Cephalic 38.6 13.1 0.6 Breech 25.5 9.2 0.6 Other 8.0 3.9 0.5

37. Weight difference in twins Audit data SHH 1998 N=45 Twin 1 is not usually bigger than twin 2

41. VTX/Non-VTX >2000g <24 weeks ECV T2 Successful >24wks & <2000g Vaginal T1 *Vaginal breech T2 Vaginal T1&T2 *Vaginal breechT2 Probable vaginal T2 Vaginal T1 ECV T2 Unsuccessful Unsuccessful Successful LSCS LSCS Probable vaginal T2 *Suitable for vaginal breech

47. ‘ The Delivery’ - Twin 2 ECV versus Breech delivery versus Internal podalic version Palpate lie immediately after delivery T1

53. UK birth rate of Triplets