Our results aligned with those from the UK study by Sutcliffe et al., which showed that advanced maternal age was associated with fewer hospital admissions at 9 months and 3 years and unintentional injuries at 9 months, 3 years, and 5 years . No statistical differences in the risk of hospital admission at 66 months among maternal age groups in our study also corroborated the null association at 5 years in the UK study. Null findings at age 5 in the present study and the UK study may suggest that the influence of other factors such as socioeconomic circumstances intensify with age. The Canadian study showed a similar trend, though the results were not statistically significant . However, the sample size was much smaller (n = 3,382) compared to our study and that of Sutcliffe et al. Although social context varies greatly among Japan, the UK, and Canada, results from all three population-based studies seemed to be in agreement.