International collaborative study of intracytoplasmic sperm injection-conceived, in vitro fertilization-conceived, and naturally conceived 5-year-old child outcomes: cognitive and motor assessments

Abstract

Objective: To date, very few studies have been conducted on the neurodevelopmental well-being of children conceived through intracytoplasmic sperm injection (ICSI). The limitations of these studies often include a lack of comparison with a demographically matched, naturally conceived (NC) group and the investigation of only very young children, with relatively small samples sizes. One study showed that there were no differences in IQ scores among ICSI-conceived, in vitro fertilization (IVF)-conceived, and NC children at 5 years of age. Unfortunately, psychomotor development was not assessed in that study. Because findings regarding these children's cognitive and motor development are inconclusive, the aim of this study was to shed more light on the cognitive and motor development of 5-year-old ICSI-conceived children.

Methods: A total of 511 ICSI-conceived children were compared with 424 IVF-conceived children and 488 NC controls. Children were recruited in 5 European countries, ie, Belgium, Denmark, Greece, Sweden, and the United Kingdom. Participation rates ranged from 45% to 96% in the ICSI and IVF groups and from 34% to 78% in the NC group. Cognitive and motor development was assessed with the Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R) and McCarthy Scales of Children's Abilities (MSCA) Motor Scale, respectively. The WPPSI-R consists of 2 major scales, ie, Verbal and Performance, each including 6 subtests. The 6 Performance Scale subtests are object assembly, geometric design, block design, mazes, picture completion, and animal pegs. The 6 Verbal Scale subtests are information, comprehension, arithmetic, vocabulary, similarities, and sentences. Scores on the Performance and Verbal Scale subtests are summed to yield the performance IQ (PIQ) and verbal IQ (VIQ), respectively. Scores on both the Performance Scale and the Verbal Scale yield the full-scale IQ (FSIQ). IQ scales have a mean score of 100 and a SD of 15. Each subtest has a mean score of 10 and a SD of 3. The MSCA consists of 6 scales, ie, Verbal, Perceptual-Performance, Quantitative, General Cognitive, Memory, and Motor Scale. In this study, only the Motor Scale was administered. This scale assesses the child's coordination during performance of a variety of gross- and fine-motor tasks. Leg coordination, arm coordination, and imitative action tests provide measures of gross-motor ability. Draw-a-design and draw-a-child assess fine-motor coordination, as revealed by the levels of hand coordination and finger dexterity. The mean score for this test is 50, with a SD of .

Results: No differences were identified among ICSI, IVF, and NC children with respect to VIQ, PIQ, or FSIQ scores of the WPPSI-R. Furthermore, there were no differences between groups regarding the discrepancy between VIQ and PIQ scores. These results were not influenced by gender, country, or maternal educational level. However, in the subgroup of firstborn children with mothers who gave birth at an older age (33-45 years), NC children obtained significantly better VIQ and FSIQ scores than did children conceived through assisted reproductive technologies. These differences in VIQ and FSIQ scores between ICSI/IVF and NC children were relative, because NC children scored <1 IQ point higher than ICSI/IVF children. Therefore, these scores show no clinical relevance. For Verbal Scale subtests, variables such as age of the mother at the time of the birth, educational level of the mother, and gender and nationality of the child interacted with mode of conception, resulting in clinically irrelevant differences between scores for the ICSI/IVF and NC groups on the arithmetic, vocabulary, and comprehension subtests. For Performance Scale subtests, these same demographic factors interacted with mode of conception for the block design, object assembly, and animal pegs subtests, again resulting in clinically irrelevant differences among groups. In the 3 groups (ICSI, IVF, and NC), we observed equal numbers of children scoring below 1 SD from the mean on the WPPSI-R and the MSCA.

Conclusions: This study includes a substantial number of children from several European countries. Apart from a few interaction effects between mode of conception and demographic variables, no differences were found when ICSI, IVF, and NC scores on the WPPSI-R and MSCA Motor Scale were compared. Nevertheless, the aforementioned interaction effects could indicate that demographic variables such as maternal age at the time of the birth and maternal educational level play different roles in the cognitive development of IVF and ICSI children, compared with NC children. Additional research is needed to explore and verify this finding. Previous studies revealed that ICSI children, in comparison with NC children, more frequently obtained scores below 1 SD from the mean on 3 subtests of the Performance Scale (object assembly, block design, and mazes) or showed a trend of 5.2% of ICSI children, compared with 2.5% of IVF children and 0.9% of NC children, obtaining a score below 1 SD from the mean, but those findings were not confirmed in this study. Here no differences were found among the 3 groups in the numbers of children scoring below 1 SD from the mean on the VIQ, PIQ, and FSIQ tests and the Verbal and Performance Scale subtests. Motor development results were somewhat more conclusive. There were no differences between the scores of ICSI, IVF, and NC children on the MCSA Motor Scale. No interaction effects were found between mode of conception and demographic variables, indicating that these results are not influenced by gender, nationality, maternal educational level, or maternal age at the time of the birth. Furthermore, equal proportions of children in all 3 groups scored below 1 SD from the mean. The results of this study are reassuring for parents who conceived through ICSI (or IVF). The findings indicate that the motor and cognitive development of their offspring is very similar to that of NC children. However, demographic factors such as maternal educational level and maternal age at the time of the birth might play different roles in the cognitive development of ICSI and IVF children, compared with NC children.