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 ¼ 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 ¼ 0.0013 and odds ratio 2.55 (95% CI 1.44-4.52). No other factors were found to be significant for the outcome.

Translocation heterozygotes have an increased risk of producing gametes with unbalanced chromosome content. This often leads to reproductive problems such as infertility, repeated miscarriages or birth of an affected child. To increase the chances of having a healthy live-born child, translocation heterozygotes often opt for preimplantation genetic diagnosis (PGD). The aim of this study was to investigate whether there is a correlation between chromosome segregation in spermatozoa from translocation heterozygotes and the number of balanced embryos produced during PGD that may be used to predict the PGD outcome. Ten male reciprocal translocation heterozygotes that went through PGD at a Stockholm PGD centre were included. We analysed 1000 spermatozoa from each patient and between 3 and 29 embryos from the total of PGD cycles that the couples went through. Fluorescence in-situ hybridization (FISH) analysis of spermatozoa and embryos was performed with the same DNA probes. We found that the proportion of balanced spermatozoa was much higher than the proportion of balanced embryos during PGD. Our results indicate that a sperm FISH analysis prior to PGD is not a reliable predictor of the PGD outcome. PGD is a valuable reproductive alternative for translocation heterozygotes with reproductive problems and should be offered to these couples.

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