The present study aimed at investigating whether neuromotor development, from birth to 14 months of age, shows seasonal, cyclic patterns in association with months of birth. Study participants were 742 infants enrolled in the Hamamatsu Birth Cohort (HBC) Study and followed-up from birth to the 14th month of age. Gross motor skills were assessed at the ages of 6, 10, and 14 months, using Mullen Scales of Early Learning. The score at each assessment was regressed onto a trigonometric function of months of birth, with an adjustment for potential confounders. Gross motor scores at the 6th and 10th months showed significant 1-year-cycle variations, peaking among March- and April-born infants, and among February-born infants, respectively. Changes in gross motor scores between the 10th and 14th months also showed a cyclic variation, peaking among July- and August-born infants. Due to this complementary effect, gross motor scores at the 14th month did not show seasonality. Neuromotor development showed cyclic seasonality during the first year of life. The effects brought about by month of birth disappeared around 1 year of age, and warmer months seemed to accelerate the neuromotor development.

[Purpose] This study aimed to examine, using the Interaction Rating Scale, the effect of social skills at 18 months of life on the subsequent development of low birthweight infants. [Participants and Methods] The study participants were made up of a total of 23 infants who were admitted to the neonatal intensive care unit of Hospital A and whose developmental indexes were followed up at the outpatient clinic for up to 3 years of age. The survey was conducted twice in each infant, at a corrected age of 18 months and at 36 full months of age. Social skills and developmental indexes were assessed at the corrected age of 18 months, meanwhile only developmental indexes were assessed at 36 full months, to examine associations. The Interaction Rating Scale was used to assess social skills. This scale measures various aspects of social development by observing caregiver-child interactions in situations wherein children are engaged in tasks more difficult for their age. [Results] The results demonstrated that social skills at 18 months were associated with the developmental indexes at 18 and 36 months, whereas more items were associated with the developmental index at 36 months. [Conclusion] The results indicate the need for early prediction of developmental delay and timely intervention, by assessing social skills in low birthweight infants.

The present study aimed at investigating whether neuromotor development, from birth to 14 months of age, shows seasonal, cyclic patterns in association with months of birth. Study participants were 742 infants enrolled in the Hamamatsu Birth Cohort (HBC) Study and followed-up from birth to the 14th month of age. Gross motor skills were assessed at the ages of 6, 10, and 14 months, using Mullen Scales of Early Learning. The score at each assessment was regressed onto a trigonometric function of months of birth, with an adjustment for potential confounders. Gross motor scores at the 6th and 10th months showed significant 1-year-cycle variations, peaking among March-and April-born infants, and among February-born infants, respectively. Changes in gross motor scores between the 10th and 14th months also showed a cyclic variation, peaking among July-and August-born infants. Due to this complementary effect, gross motor scores at the 14th month did not show seasonality. Neuromotor development showed cyclic seasonality during the first year of life. The effects brought about by month of birth disappeared around 1 year of age, and warmer months seemed to accelerate the neuromotor development.