One-cell biopsy significantly improves the outcome of preimplantation genetic diagnosis (PGD) treatment: retrospective analysis of 569 PGD cycles at the Stockholm PGD centre

study question: What are the significant factors that influence the outcome of a PGD treatment? summary answer: The age of the woman and the number of biopsied cells per embryo are of significant importance for a successful PGD treatment. what is known already: Younger women are more likely to succeed with an IVF treatment. study design, size, duration: Cohort study, retrospective analysis of 569 PGD cycles, 1996–2009. participants, setting, methods: 256 couples and 569 PGD treatments at ‘Stockholm PGD centre’. At this centre after 2003, a 1-cell policy was applied, when possible, with respect to the reliability of the diagnostic test and since 2009, 1-cell biopsy policy was also applied for monogenic disorders. main results and the role of chance: The women under 36 years of age were three times more likely to get pregnant after PGD treatment, P 1⁄4 0.003 and odds ratio 3.1 [95% confidence interval (CI) 1.5–6.5]. The 1-cell biopsy cycles were twice as likely to result in a pregnancy in comparison with cycles were 2 cells were removed from the embryo, P 1⁄4 0.0013 and odds ratio 2.55 (95% CI 1.44– 4.52). No other factors were found to be significant for the outcome. limitations, reasons for caution: Retrospective analysis with 1and 2-cell biopsies at different times. wider implications of the findings: The results will have an impact on the implementation of PGD in general, thereby making it possible to significantly improve the treatment outcome. study funding/competing interest: The work was supported by grants from the Swedish Medical Research Council and the Stockholm County Council. No competing interest.