The status of preimplantation genetic testing in the UK and USA.

study questionHas the number of preimplantation genetic testing (PGT) cycles in the UK and USA changed between 2014 and 2016? SUMMARY ANSWER: From 2014 to 2016, the number of PGT cycles in the UK has remained the same at just under 2% but in the USA has increased from 13% to 27%. WHAT IS KNOWN ALREADY: PGT was introduced as a treatment option for couples at risk of transmitting a known genetic or chromosomal abnormality to their child. This technology has also been applied as an embryo selection tool in the hope of increasing live birth rates per transfer. ART cycles are monitored in the UK by the Human Fertilisation and Embryology Authority (HFEA) and in the USA by the Society for Assisted Reproductive Technology (SART). Globally, data are monitored via the ESHRE PGT Consortium. STUDY DESIGN, SIZE, DURATION: This cross-sectional study used the HFEA and SART databases to analyse PGT cycle data and make comparisons with IVF data to examine the success of and changes in patient treatment pathways. Both data sets were analysed from 2014 to 2016. The UK data included 3385 PGT cycles and the USA data included 94 935 PGT cycles. PARTICIPANTS/MATERIALS, SETTING,

methodsFollowing an extensive review of both databases, filters were applied to analyse the data. An assessment of limitations of each database was also undertaken, taking into account data collection by the ESHRE PGT Consortium. In the UK and USA, the publicly available information from these datasets cannot be separated into different indications. MAIN RESULTS AND THE ROLE OF CHANCE: The proportion of PGT cycles as a total of ART procedures has remained the same in the UK but increased annually in the USA from 13% to 27%. Between 2014 and 2016 inclusive, 3385 PGT cycles have been performed in the UK, resulting in 1074 PGT babies being born. In the USA 94 935 PGT cycles have been performed, resulting in 26 822 babies being born. This gave a success rate per egg collection for PGT of 32% for the UK and 28% for the USA. Analysis of the data by maternal age shows very different patient populations between the UK and USA. These differences may be related to the way PGT is funded in the UK and USA and the lack of HFEA support for PGT for aneuploidy. LIMITATIONS, REASONS FOR CAUTION: Data reported by the HFEA and SART have different limitations. As undertaken by the ESHRE PGT Consortium, both data sets should separate PGT data by indication. Although the HFEA collects data from all IVF clinics in the UK, SART data only represent 83% of clinics in the USA. WIDER IMPLICATIONS OF THE

findingsWorldwide, a consistent reporting scheme is required in which success rates can convey the effectiveness of PGT approaches for all indications. STUDY FUNDING/COMPETING INTEREST(S): No specific funding was obtained and there are no competing interests to declare that are directly related to this project. Joyce Harper is the director of the Embryology and PGD Academy, which offers education in these fields.