Bayley Scales of Infant Motor Development (BSID-II) – Article Summary
Title: Gross Motor Trajectories During the First Year of Life for Preterm Infants With Very Low Birth Weight
Authors: Yu-Han Su, Suh-Fang Jeng, Wu-Shiun Hsieh, Yu-Kang Tu, Yen-Tzu Wu, Li-Chiou Chen
Citation: Su et al. Gross Motor Trajectories During the First Year of Life for Preterm Infants With Very Low Birth Weight. Physical Therapy. Volume 97, Issue 3, 1 March 2017, Pages 365–373, https://doi.org/10.1093/ptj/pzx007
Purpose: In premature, low birth weight infants, there has been a lack of studies showing motor trajectories. It is difficult to investigate premature infants because of different developmental patterns and some infant’s recovery from premature complications. This study’s goal was to monitor premature infants’ motor development throughout their first year of life. The study then wanted to determine if they could predict the infants’ motor development by the second year of life. The study also analyzed different socioeconomic and perinatal factors that could influence motor development.
Study Population: 342 very low birth weight infants were used for the study. The participants came from 3 hospitals in Taiwan, that were in previous studies. Inclusion criteria was birth weight <1500 g, < 37 weeks, no congenital or hereditary diseases. Exclusion criteria were severe neonatal diseases and complications.
Methods/Interventions: The socioeconomic and perinatal factors were studied by interviewing parents and chart review. The study used 2 outcome measures, the Alberta Infant Motor Scale (AIMS) and the Bayley scales of Infant and Toddler development (BSID-II). The AIMS was completed at 2, 4, 6, 9, and 12 months to monitor motor development, and at 24 months the BSID-II was administered to measure motor and cognitive development. This study did not use the behavior scale in the BSID-II.
Results: Researchers used a growth mixture modeling (GMM) in order to divide the infants in to 3 subgroups with similar motor developments. The 3 groups were stably normal (55%), deteriorating (32%), and persistently delayed (13%). Stably normal infants scored a typical motor progression in the AIMS, the deteriorating group scored normal at first then decrease in the AIMS score starting at 6 months, and the persistently delayed infants scored slightly delayed around 4 months then continued to decrease in scores. The infants that returned at 24 months were studied using a regression analysis, to see if the motor and cognitive development displayed in the first year could predict motor development at 24 months. Infants in the deteriorating motor trajectory group were more likely to have borderline motor and cognitive delays at 24 months. Infants that were persistently delayed were even more likely to have borderline motor and cognitive delays. The regression analysis used different cutoff indices, and with the lower cutoff the infants had higher risk of more severe motor and cognitive delays. Factors such as being male, having bronchopulmonary dysplasia, and low birth weight were more common in deteriorating trajectory. The persistently delayed group was more like to have bronchopulmonary dysplasia, stage III or IV retinopathy of prematurity, major brain damage, and low birth weight.
Strengths: In past studies, it was more difficult to study motor development, because the variability it can have. This study was the first study to be able to make 3 distinct subgroups to better analyze the motor development of low birth weight infants. This study’s large sample size, was able to complete a follow-up in order to analyze the variability and stability over the 24 months.
Weaknesses: Out of the three trajectory groups, the persistently delayed group had a lot fewer subjects than any other group. Because the exclusion criteria did not include infants with severe diseases, this may have limited the sample power in the persistently delayed group. The study results state there was no effect from the socioeconomic factors, but there was not much time for the parents to implement enough intervention to have an effect on the infants’ outcomes.
Conclusion: The study was able to develop 3 early motor trajectories, stably normal, deteriorating, and persistently delayed for very low birth weight infants. Even the stably normal preterm infants need to be continuously monitored at the beginning of their development, because normal complications with these infants. These groups were able to predict the motor development at 24 months. They determined that socioeconomic factors like environment and parents were not factors that influenced motor development. The study did conclude that the motor trajectories and some perinatal factors can help the families determine needs for early intervention for infants.
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Great article review, Monica! I thought it was very interesting that these motor trajectories hadn’t been established previously. Additionally, I agree with you in the fact that the sample size this study has is a very big strength. I am curious as to why being male is more common in the deteriorating trajectory. Overall, I feel that these results could be very beneficial for PTs as a guide to help determine typical development for premature infants that they are working with. Also, these results may be beneficial to help determine when PT services are needed for premature infants.