Children Conceived Using Intracytoplasmic Sperm Injection Do Not Have an Increased Risk of Delayed Mental Development at 5 Years of Age

Abstract

Since intracytoplasmic sperm injection (ICSI) was first used a decade ago, there has been concern about possible long-term adverse effects on health, psychosocial status, and developmental outcomes. The initial controlledstudy of ICSI children 1 year of age, using the Bayley Mental Development Index, found an increased risk of delayed mental development compared with children conceived naturally or using in vitro fertilization (IVF); the relative risk was 9.2. The present study reassessed development at age 5 years using a more accurate measure of cognitive ability, the Wechsler Preschool and Primary Scales of Intelligence-Revised (WPPSI-R). Mental development was assessed in 97 ICSI, 80 IVF, and 110 naturally conceived (NC) children. They included 213 of the original cohort of 253 children. The mean age at the time of assessment was 61 months. Mean values for the WPPSI-R were within the normal range in all 3 groups, and no between-group differences were apparent. Delayed full-scale IQ scores (IQ below 85) were recorded for 5.2% of ICSI, 2.5% of IVF, and 0.9% of NC children. Normal scores were obtained for 58.7%, 61.2%, and 56.4% of children, respectively. Accelerated scores (IQ above 115) were recorded for 36.1% of the ICSI group, 36.3% of IVF children, and 42.7%% of NC children. There were no significant between-group differences in any of these 3 categories. The likelihood of a delayed full-scale IQ score in the ICSI group was not significantly increased when compared with the other groups, individually or together. On multivariate analysis, the only significant and independent predictor of a below-average full-scale IQ score was a lower maternal educational level. Within the ICSI group, full-scale IQ was not related to the type of defect in paternal sperm. These findings should reassure parents of children conceived using ICSI that the procedure does not impair long-term cognitive function. The genetic influence of parental cognitive ability appears to be more important than the mode of conception.