title: The impact of assisted hatching on live birth rates and outcomes of assisted conception: a systematic review.
abstract: BACKGROUND
  During the past decade in the UK, only one in six cycles of assisted conception has resulted successfully in a live birth. Assisted hatching (AH) has been proposed to improve outcome. This systematic review of randomized controlled trials addresses primary outcomes of live birth, clinical pregnancy and embryo implantation.
  
  
  METHODS
  Trials on post-fertilization disruption of the zona pellucida were identified from the Cochrane Controlled Trials Register, MEDLINE, EMBASE and published bibliographies. Outcomes were analysed using random effects meta-analysis, sensitivity analysis, sub-grouping and meta-regression.
  
  
  RESULTS
  Of 23 included trials recruiting 2572 women, only six reported live birth data. AH had no significant effect on live birth (OR 1.21, 95% CI 0.82-1.78). There was a significant benefit of AH on clinical pregnancy (OR 1.63, 95% CI 1.27-2.09), especially in the sub-group of women with previous failure of assisted conception (OR 2.33, 95% CI 1.63-3.34). Meta-regression suggested that AH might be more useful in older women. Implantation data were not considered valid for statistical analysis. The methodological quality of included trials was sub-optimal.
  
  
  CONCLUSIONS
  AH probably enhances clinical pregnancy, especially in women with previous failure of assisted conception treatment and in older women; however, trials were of poor quality and so may be biased. Better quality trials reporting live birth are required to confirm any positive effects on the 'take-home-baby rate'.
authors.affiliation: Academic Unit of Obstetrics, Gynaecology and Reproductive Healthcare, St Mary's Hospital, Manchester, UK.
authors.forename: Edmond
authors.initials: E
authors.lastname: Edi-Osagie
authors.forename: Lee
authors.initials: L
authors.lastname: Hooper
authors.forename: Mourad W
authors.initials: MW
authors.lastname: Seif
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology; D001723:Birth Rate; D004210:Dissection; D010064:Embryo Implantation; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D015994:Incidence; D011247:Pregnancy; D011256:Pregnancy Outcome; D018873:Pregnancy Rate; D016032:Randomized Controlled Trials as Topic; D027724:Reproductive Techniques, Assisted; D015044:Zona Pellucida