SUMMARY ANSWER The available high- quality evidence indicates that specific treatments may give rise to different effects on cognitive development , with certain treatments , including ICSI , associated with cognitive impairment .
STUDY QUESTION Does  fertility treatment  influence cognitive ability in school aged children , and does the impact vary with the type of treatment ?
WHAT IS KNOWN ALREADY Previous review s of the literature concerning cognitive outcomes among children conceived with medical assistance have concluded that study findings are generally ' reassuring ' , but limited attention has been paid to the quality of this research .
In addition , no review has separately assessed the range of treatment modalities available , which vary in invasiveness , and thus , potentially , in their effects on developmental outcomes .
Cognitive and psychomotor development of 5- to 6-year-old singletons born after PGD: a prospective case-controlled matched study.
STUDY QUESTION Do preschool preimplantation genetic diagnosis ( PGD ) children differ in their cognitive and psychomotor development from children born after ICSI and spontaneous conception ( SC ) ? SUMMARY ANSWER The cognitive development of PGD pre-schoolers was comparable to children born after ICSI and SC but motor development differed between ICSI and SC groups . STUDY DESIGN , SIZE DURATION The cognitive abilities and motor skills of 5- to 6-year-old singletons born after PGD ( n = 47 ) were assessed in comparison with 49 ICSI and 48 SC children in a prospect i ve , case-controlled , matched follow-up study between April 2011 and May 2013 . PARTICIPANTS / MATERIAL S , SETTING , METHODS PGD singletons , ICSI and SC children of preschool age were examined with the Wechsler Preschool and Primary Scale of Intelligence ( WPSSI-III-NL ) and the Movement ABC ( M ABC ) . The WPSSI-III-NL revealed scores for Full IQ , Verbal IQ and Performance IQ . The M ABC yields a total score and comprising scores for measurements of balance , dexterity and ball skills . Since embryo biopsy is the only technical difference between the PGD and ICSI procedures , ICSI children were included as controls . These children were part of a Dutch-speaking cohort of children conceived after assisted reproduction technology ( ART ) at the Universitair Ziekenhuis Brussel ( UZ Brussel ) who received longitudinal follow-up . The SC children acted as a second control group similar to the fertile PGD sample and in contrast to the ICSI group . The SC group was recruited through announcements in a variety of media . The children were matched for age , gender , birth order and educational level of the mother . The assessment s carried out for the ART groups were blinded whenever possible . The data were analysed using analysis of covariance ( ANCOVA ) and partial eta squared ( η(2 ) ) , which was used as a measurement of effect size . MAIN RESULTS AND THE ROLE OF CHANCE The overall cognitive development of PGD singletons did not differ from controls [ P = 0.647 , η(2 ) = 0.006 ; 95 % confidence interval ( CI ) ( 0 , 0.043 ) ] . The partial IQ scores for Verbal and Performance intelligence revealed similar results . Analysis of motor development based on the total score as well as subscales did indicate a significant difference between the three conception groups [ P = 0.033 , η(2 ) = 0.050 , 95 % CI ( 0 , 0.124 ) ] . Post hoc analysis indicated that the significant difference was situated between performances of ICSI and SC children . Balance capacities [ P = 0.004 , η(2 ) = 0.079 , 95 % CI ( 0.025 , 0.163 ) ] and its post hoc analysis yielded equivalent results . Motor capacities of PGD singletons , however , did not differ from any of the two other conception groups . LIMITATIONS , REASONS FOR CAUTION Given that we only assessed Caucasian singletons born after PGD , caution is required when drawing more general inferences from our results . The small sample size may be a limitation . A priori power analysis , however , revealed that at least 52 children per group were needed to detect a medium effect and 80 % power using ANCOVA . Originally our sample met this threshold but we had to exclude six cases in order to remove outliers and due to missing data . WIDER IMPLICATION S OF THE FINDINGS Long-term follow-up of children born after embryo biopsy , in this case for PGD , is needed to confirm that the development of these children remains comparable to ICSI and SC children . Our findings do support the safety of the PGD technique and will reassure patients with hereditary genetic diseases regarding the health of their future offspring conceived with PGD . STUDY FUNDING /COMPETING INTERESTS Funding for this study was obtained from the OZR ( Research group of the Vrije Universiteit Brussel ) , the FWO ( Fonds Wetenschappelijk Onderzoek ) and the Wetenschappelijk Fonds Willy Gepts . The UZ Brussel and the Centre of Medical Genetics received funding from pharmaceutical firms for data collection . UZ Brussel and the Centre for Medical Genetics have received many educational grants for organizing the data collection , from IBSA , Ferring , Organon , Shering-Plough , Merck and Merck Belgium . M.B. has received consultancy and speaker 's fees from Organon , Serono Symposia and Merck
SUMMARY ANSWER The available high- quality evidence indicates that specific treatments may give rise to different effects on cognitive development , with certain treatments , including ICSI , associated with cognitive impairment .
STUDY QUESTION Does  fertility treatment  influence cognitive ability in school aged children , and does the impact vary with the type of treatment ?
WHAT IS KNOWN ALREADY Previous review s of the literature concerning cognitive outcomes among children conceived with medical assistance have concluded that study findings are generally ' reassuring ' , but limited attention has been paid to the quality of this research .
In addition , no review has separately assessed the range of treatment modalities available , which vary in invasiveness , and thus , potentially , in their effects on developmental outcomes .