Motor Development of Triplets: A Japanese Prospective Cohort Study

Abstract

We analyzed whether motor development in early life is different between singletons and triplets in Japan. The motor development was reported by mothers by postal questionnaire for 1,121 triplet children and in regular health check-ups for 13,906 singleton children. Children who were suspected of having neurological abnormality or disability were excluded from the analysis. The ages of milestone achievements were significantly higher in triplets for each outcome compared to singletons. Further, after adjustment for gestational age, birthweight, and birth length, the differences were significant for maintaining head, sitting alone and standing holding on. In children with birthweight of 2 kg or more, the ages of milestone achievements were significantly higher in triplets for each outcome compared to singletons, except walking holding on. Moreover, after adjustment for the confounding factors, the differences were significant for sitting alone and walking independently. On the contrary, singletons attained motor development facilitating crawling, walking holding on, and walking independently slower than triplets among those children with birthweight of 2 kg or less after adjustment for gestational age. In conclusion, triplets are overall at higher risk for the delay of gross motor milestones as compared to singletons independently of birth-related factors. In contrast, among children with a birthweight of less than 2 kg, singletons showed slower motor development than triplets after adjusting for gestational age. There is an obvious need to apply developmental standards that consider at least both multiple birth status (singleton, twin or triplet) and birthweight.

Triplets, birthweight, and handedness

“…Many previous studies have found neurological deficits to relate to VLBW, preterm birth, and multiples (21,(33)(34)(35)(36)(37)(38)(39). A metaanalysis indicated that non-right-handedness is more common in those with intellectual disabilities compared with those with no intellectual disability (40).…”

Social Modifications of the Multiple Birth Effect on IQ and Body Size: a Population‐Based Study of Young Adult Males

“…We found evidence for this in Japanese children, because very low birthweight triplets were ahead of very low birthweight singletons in motor development in early childhood. 7 Further, we used no information on zygosity because it was available only for part of the cohort, and stratification of the results by zygosity would have decreased the statistical power in the analysis stratified by parental SEP and maternal birth cohort. However, in our previous study in which we used self-reported zygosity and some of the same data as in this study, we found no major differences in height, BMI or muscle strength between monozygotic and dizygotic twins.…”

“…Thus, low birthweight and low gestational age is expected to show different associations with the development of singletons when compared with twins and triplets. We found evidence for this in Japanese children, because very low birthweight triplets were ahead of very low birthweight singletons in motor development in early childhood . Further, we used no information on zygosity because it was available only for part of the cohort, and stratification of the results by zygosity would have decreased the statistical power in the analysis stratified by parental SEP and maternal birth cohort.…”

“…With regard to physical development, evidence suggests that twins are lighter than singletons in late adolescence despite their rapid catch‐up growth in early childhood . Studies of the development of triplets are rare, but reports from Japan suggest that triplets fall behind singletons in their motor development in early childhood as well as growth in height and weight in mid‐childhood.…”

The West Japan Twins and Higher Order Multiple Births Registry

“…Physical growth and development features of twins and triplets in childhood were also extensively analyzed as part of the study (Yokoyama et al, 1995d, 2005, 2008, 2009, 2011a, 2011b, 2012). The present dataset represents the largest triplet sample in the world for which accurate data on age after birth are available.…”