Cognitive and Behavioral Development in Triplets and Twins: A Follow-Up Study

Abstract

Objective: Triplet pregnancies have a high risk of perinatal complications. While cognitive and behavioral challenges during childhood have been documented in twins, research on triplets remains limited. This prospective follow-up study aims to assess intellectual and behavioral abilities in triplets and twins.

Method: Intellectual and behavioral abilities were evaluated using the intelligence quotient (IQ) and child behavior checklist scores, respectively. First, we characterized these abilities within the triplet cohort. Second, we examined their association with birthweight and gestational age. Third, we compared those abilities between triplets and twins.

Results: A total of 52 triplet sets and 663 twin pairs participated. Among triplets, total IQ was positively associated with maternal socio-economic status and gestational age. Additionally, 13.57% of triplets exhibited a discrepancy of ≥ 20 points between verbal and performance IQ, potentially indicating a risk for learning difficulties. Comparative analysis revealed statistically significant differences in intellectual abilities between triplets and twins, dependent on maternal socio-economic status. Among children of mothers with lower socio-economic status, triplets scored significantly lower on IQ compared to twins. In contrast, no significant differences were found in the subgroup of mothers with high socio-economic status. Furthermore, no differences in behavioral abilities were found between triplets and twins.

Conclusion: Total IQ in triplets was positively associated with gestational age and maternal socio-economic status. Comparative analysis showed that triplets of mothers with lower socio-economic status had significantly lower IQ than twins. These findings underscore the pivotal role of maternal socioeconomic conditions in shaping cognitive development. Ongoing longitudinal follow-up of the triplet cohort will further clarify developmental outcomes in adulthood.