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UOG Journal Club: Prospective risk of late stillbirth in monochorionic twins: A regional coh…

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This Journal Club presentation provides a summary and discussion of the following free access article published in UOG:

Prospective risk of late stillbirth in monochorionic twins: A regional cohort study
Southwest Thames Obstetric Research Collaborative (STORK)
Volume 39, Issue 5, Date: May 2012, pages 500-504

This can be accessed here:
http://onlinelibrary.wiley.com/doi/10.1002/uog.11110/abstract

Published in: Health & Medicine
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UOG Journal Club: Prospective risk of late stillbirth in monochorionic twins: A regional coh…

  1. 1. UOG Journal Club: May 2012Prospective risk of late stillbirth in monochorionic twins: a regional cohort study Southwest Thames Obstetric Research Collaborative (STORK) Volume 39, Issue 5, Date: May 2012, pages 500–504 Journal Club slides prepared by Dr Asma Khalil (UOG Editor for Trainees)
  2. 2. Stillbirth rate in twin pregnancy Current evidence 10 Large numbers (n = 35 647) 9 But no data on chorionicity Stillbirth rate per 1000 8 7 fetuses at risk 6 5 4 3 Twins 2 Singleton 1 0 28 30 32 34 36 38 40 42 Gestational age (weeks) Joseph K et al., BMC Pregnancy Childbirth 2003
  3. 3. Cumulative perinatal loss rate in twins Current evidence Monochorionic Chorionicity data But small numbers (n = 467)Cumulative loss rate (%) Fetal loss: MC DC Pregnancies (%) 12.7 2.5* Fetuses (%) 12.2 1.8* Perinatal loss: Dichorionic Pregnancies (%) 4.9 2.8 Fetuses (%) 2.8 1.6 Gestation (weeks) * P < 0.05 Sebire NJ et al., BJOG 1997
  4. 4. Prospective risk of late stillbirth in monochorionic twins: a regional cohort study STORK, UOG 2012ObjectiveEvaluate the prospective risk of late stillbirth in a large regionalcohort of twin pregnancies of known chorionicity Retrospective data; 3005 twin pregnancies delivered after 26 weeks from 2000 to 2009
  5. 5. MethodologyInclusion criteria Exclusion criteria1) Confirmed diamniotic twin 1) Unknown chorionicity pregnancy at 11 weeks 2) Delivery < 26 weeks2) 9 hospitals in the Southwest Thames 3) TOP region of England 4) Stillbirth with a birth weight of < 500g3) 2000-2009 Data sources•Scan data: computerized search of each hospital’s obstetric ultrasound computerdatabase of all twins at 11–14-week nuchal scan•Stillbirth data: Centre for Maternal and Child Enquiries (CMACE)  Mandatory national register of all stillbirths  GA at IUD and delivery•Computerized maternity records were cross-linked to stillbirth data
  6. 6. SOUTHWEST THAMES OBSTETRIC RESEARCH COLLABORATIVE (STORK) Nine UK hospitals, 16 collaborators
  7. 7. Pregnancy management 11–14 weeks Delivery•GA according to the CRL • Mode according to patient’s•Chorionicity (lambda/T-signs) decision and local clinical practice 20–22 weeks • Routine IOL ≥ 38 weeks•Routine anomaly scan • Elective CS ≥ 36 weeks for MC and ≥ 37 weeks for DC twins 3rd trimester•Ultrasound every 3–5 weeks Analysis•Scans more frequently • SB risk: derived for each 2-weekas clinically indicated GA interval from 26 weeks•MC twins had additional scans at • SB risk expressed per fetus17 and 19 weeks (for TTTS)
  8. 8. Results MC pregnancies DC pregnancies Live births (n = 528) (n = 2424)GA at delivery (weeks) 36 (34–37) 37 (35–38)*Birth weight centile 18.4 (4.0–44.8) 22.9 (6.2–50.7)* Stillbirths MC pregnancies DC pregnancies (n = 21) (n = 32) GA at death (weeks) 32 (31–34) 34 (32–36) Birth weight centile 3.9 (0.2–28.3) 1.1 (0.1–10.0) * P < 0.05
  9. 9. Timing of birth in twin pregnancy Modal time of delivery MC = 36–37 weeks DC = 37–38 weeksBirth (%) Monochorionic Dichorionic Gestational age (weeks)
  10. 10. Late stillbirth risk in twin pregnancy 9 8 1000 ongoing fetuses 7 Monochorionic Stillbirth risk per 6 5 4 3 Dichorionic 2 1 0 26 28 30 32 34 ≥ 36 Gestational age (weeks)SB risk in MC twins did not change significantly between 26 and 36 weeks (OR = 1.85 (0.3–13.2))
  11. 11. Late stillbirth risk in twin pregnancy Risk of stillbirth compared to 26+0–27+6 weeks Monochorionic Dichorionic >36 >36 Gestational age Gestational age 34-36 34-36 (weeks) (weeks) 32-34 32-34 30-32 30-32 28-30 28-30 0.1 1 10 0.1 1 10 Odds ratio Odds ratioTotal stillbirth rate: MC twins = 19.1 (12.5–29.1) fetuses/1000 ongoing fetuses DC twins = 6.5 (4.6–9.2) ) fetuses/1000 ongoing fetuses OR = 2.97 (95% CI 1.7–5.28)
  12. 12. Strengths Current study Previous studies•Management according to a • Smaller numbersprotocol consistent with currentclinical practice • No standardized protocol for fetal•Modal time of delivery for MC surveillanceand DC twins of 36 and 37 wk • Elective delivery of many MC twins•Largest twin cohort to providedata on chorionicity-related risk of before 37 weekslate SB Limitations• Retrospective design (validation of the ultrasound database against delivery suite and national SB registers)• Assumptions made about GA at which IUD was diagnosed
  13. 13. Stillbirth versus prematurity Stillbirth riskTotal stillbirth rate >26 weeks approaches 2% in MC twins Late preterm delivery1) Infant death rate >32 weeks is 1%2) Respiratory distress syndrome at 32 weeks 5%3) Cerebral palsy is 3 x higher at 34 weeks than at term
  14. 14. Prospective risk of late stillbirth in MC twins STORK, UOG 2012 Conclusion The risk of SB in MC twins does not appear to increase significantly near term The data do not support a policy of elective delivery at less than 36 weeks in uncomplicated MC twins
  15. 15. Prospective risk of late stillbirth in MC twins STORK, UOG 2012 Discussion points• What is your local hospital policy for timing of delivery of MC and DC twins?• Is the clinical evidence for your local policy robust?• How did the researchers capture all twin pregnancies in this cohort?• How did the researchers capture all the stillbirths from this cohort?• Was the stillbirth risk in MC different from that of DC twins?• Did the stillbirth risk in MC twins increase significantly at any gestational age?• Do the risks of continuing MC pregnancy beyond 34 weeks’ gestation outweigh the risks of preterm delivery?

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