The effect of preimplantation genetic screening on neurological, cognitive and behavioural development in 4-year-old children: follow-up of a RCT.
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STUDY QUESTION: Does embryo biopsy inherent to preimplantation genetic screening (PGS) affect neurological, cognitive and behavioural development of 4-year-old children? SUMMARY ANSWER: PGS does not seem to affect neurological, cognitive and behavioural development of 4-year-old singletons; however, our data suggest that it may be associated with altered neurodevelopment in twins. WHAT IS KNOWN ALREADY: Evidence concerning the safety of PGS on neurodevelopmental outcome in offspring is scarce. The present study provides information on neurodevelopmental, cognitive and behavioural outcome of 4-year-old PGS offspring. STUDY DESIGN, SIZE, DURATION: A prospective, assessor-blinded follow-up study of children born to women who participated in a multi-centre RCT on the effect of IVF with or without PGS. PARTICIPANTS/MATERIALS, SETTING, METHODS: At 4 years, 49 children (31 singletons, 9 sets of twins) born following IVF with PGS and 64 children (42 singletons, 11 sets of twins) born following IVF without PGS (controls) were assessed (post-natal attrition 18%). Neurological development was evaluated with the standardized, age-specific and sensitive neurological examination according to Hempel, resulting in a neurological optimality score (NOS), a fluency score and the rate of adverse neurological outcome. Primary outcome was the fluency score, as fluency of movements is easily reduced by subtle dysfunction of the brain. Cognitive development was evaluated with the Kaufman Assessment Battery for Children; behavioural development was evaluated with the Child Behavior Checklist. The effect of PGS was analysed with a mixed effects model. MAIN RESULTS AND THE ROLE OF CHANCE: Based on the intention to treat analysis, neurodevelopmental outcome of PGS children was similar to that of controls. However, additional analyses indicated that PGS affected neurodevelopmental outcome of twins in a different way than that of singletons. The fluency score of singletons born following PGS was similar to that of control singletons [mean values, 95% confidence intervals (CIs): 12.2 (11.5;12.8) and 12.2 (11.6;12.8)], respectively, P = 0.977) that was also true for the other neurodevelopmental parameters. The fluency score of PGS twins was significantly lower than that of control twins [mean values, 95% CIs: 10.6 (9.8;11.3) and 12.3 (11.5;13.1)], respectively, P = 0.001); the same was true for the NOS. In addition, PGS in twins was associated with a higher sequential intelligence quotient score. On the other hand, other neurodevelopmental parameters were similar for PGS twins and control twins. Post hoc sample size calculation for the primary outcome parameter, the fluency score, indicated that the study groups, including the subgroups of singletons and twins, were adequately powered. LIMITATIONS, REASONS FOR CAUTION: We assessed singletons and twins who contributed to the generalizability of the study. A limitation of our study is the relative small size of our study groups and the selective dropout in both groups (dropouts PGS group: higher gestational age; control group: less well-educated parents). These preclude the conclusion that PGS per se is not associated with neurodevelopmental, cognitive and behavioural problems in singletons and the conclusion that PGS is associated with altered neurodevelopmental outcome in twins. WIDER IMPLICATIONS OF THE FINDINGS: The need for careful long-term monitoring of children born following embryo biopsy remains, as it is still applied in the form of PGD and it is still unknown whether embryo biopsy affects long-term neurodevelopmental outcome.
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