Acquisition process of unsupported sitting-up in motor development of infants in Japan

Abstract

According to Pikler’s comprehensive observations of developmental milestones, most of infants become able to sit up unsupported after they began creeping on the ground. In Japan, the acquisition of sitting has been adopted as one of the important developmental indicators of infants. The age of acquisition of sitting-up of infants and its individual differences have been reported in previous research; however, the acquisition process has not been well investigated for infants after Pikler’s observations during 1940s-1960s. The present study investigated the process of acquiring the sitting posture from creeping and crawling in infants, by a questionnaire collected from 260 Japanese parents in 31 nursery school in three prefectures (Hyogo, Okayama and Tottori) of Western Japan. The results showed that 61.2% of infants sat up unsupported earlier than they began creeping or hands-and-knees crawling. The study further revealed that cultural reasons and parents’ misinterpretation of the definitions regarding milestone postures advised by the current governmental handbook for mother and child health may attribute to the reversal of these two major milestone sequences in the case of Japanese infants. We propose that a revision of the related mother-child handbook with appropriate words of motor developmental milestones with their clear definitions is recommended. This study also suggests the needs of further investigations of the effects of environmental factors related to the spontaneous movement of infants, such as the use of infant equipment, on motor development of infants.