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Suzanne Hodgson

Suzanne Hodgson. Researcher in Statistics & Epidemiology. SCAAC – 12 June 2013. Updated Blastocyst Analysis. Introduction. Two years ago we looked at benefits and risks of blastocyst transfers, compared with cleavage stage transfers

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Suzanne Hodgson

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  1. Suzanne Hodgson • Researcher in Statistics & Epidemiology • SCAAC – 12 June 2013 • Updated Blastocyst Analysis

  2. Introduction • Two years ago we looked at benefits and risks of blastocyst transfers, compared with cleavage stage transfers • Areas of concern were success rates, monozygotic twinning, gestation & birth weight, abnormalities and the sex ratio. • At the time data was up to 2008, now 2010 for births 2011 for pregnancies

  3. Last time we saw.. There was some evidence that: • pregnancy and birth rates are higher for BTs than CTs • DBT has very high MB rates, blastocysts may result in more MZ twins; • the sex ratio is skewed in favour of males, particularly after eSET There did not seem to be evidence that: • there is a difference in birth weight • there is a difference in gestation

  4. Change over time • Then: BTs were a relatively new procedure in the UK, but growing. • 7% in 2006, 12% in 2008 and in 2010 blastocysts formed nearly a quarter of all embryo transfers • 2012/3 – over 40%, and still with a steady upward trend.

  5. Changes in embryo stage at transfer • 2008 to June 2012

  6. Pregnancies and birth • Must take great care comparing CT and BT success rates – they are likely to be different types of patient. • Cleavage: • pregnancy rate per transfer 28.2% (2011) • live birth per transfer 25.8% (2010) • Blastocyst: • pregnancy rate per transfer 46.3% (2011) • live birth per transfer 41.4% (2010)

  7. Age specific live birth rates per ET 2010

  8. Age specific pregnancy rates per ET • 2011

  9. Multiple births Overall in 2010, 20.1% of live births after CTs were of two or three babies, and 19.9% after BTs. High multiple birth rate after double BTs – 34.8% compared with 24.6% after DCTs. In women under 35 this is even more pronounced, 40.0% of births are multiples after DBT

  10. Monozygotic twins Few outcomes annually so data has been aggregated over 2 years There is much variation year to year Can only count where babies born is greater than embryos transferred

  11. Gestation No significant difference between CT and BT for singletons or twins

  12. Birth weight - singletons Initially singletons only Cleavage mean birthweight: • 3,247g (CI:3,231 – 3,264g) Blastocyst mean birthweight: • 3,237g (CI: 3,256– 3,259g) As before, not statistically significantly different

  13. Birth weight - multiples Multiples may have very different birth weights but same gestation Looked at whether one or more babies were of low birth weight (<2,500g) Very similar proportions after CT, 69.8% and BT, 68.9% Similar to that seen last time, and around the same as the NPEU analysis 2006 (66%)

  14. Congenital abnormities Abnormalities are recorded in live births, still births, terminations & miscarriages. For babies born alive, 2010 saw 773 congenital abnormalities, 27 uncertain RR for 2010: 0.49 (95% CI: 0.41 – 0.57) RR for aggregated 2009 & 10: 0.39 (95% CI: 0.34 – 0.44) Apparent reduction in risk after BT.

  15. Sex ratio (2008)

  16. Sex ratio (2010)

  17. Conclusions The proportion of embryos transferred at blastocyst stage continues to increase, now nearly half. We now have more evidence that: • success rates are higher for BTs than CTs • blastocysts may result in more MZ twins; DBT has very high MB rates There does not seem to be evidence that: • there is a difference in birthweight or gestation There is less evidence of: • skewing of the sex ratio

  18. Suzanne.Hodgson@hfea.gov.uk

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