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Development of postural asymmetry in premature human infants
Insights
Premature infants show a developing head-turning preference to the right, similar to full-term infants by 39 weeks. This head position asymmetry appears influenced by both fetal and uterine factors.
Area of Science:
- Developmental Pediatrics
- Neonatology
- Neuroscience
Background:
- Head position and turning preferences are crucial developmental markers in infants.
- Understanding early asymmetries in premature infants is vital for identifying potential developmental trajectories.
Purpose of the Study:
- To investigate the development of head position preference in premature infants.
- To compare head position patterns in premature infants with those of term infants.
- To explore potential determinants of head position asymmetry in early infancy.
Main Methods:
- Observation of head position in 95 infants (30-37 weeks gestational age) weekly until 39 weeks conceptional age.
- Data collection involved recording head position every 15 minutes for 2 hours per session.
- Analysis compared head position duration to the left versus right, and responses from a midline position.
Main Results:
- Premature infants showed a significant increase in right-sided head preference from 35 weeks onwards.
- By 39 weeks conceptional age, nearly 90% of infants spent over 80% of their time with their head to the right.
- Unlike term infants, premature infants showed no significant bias when released from a midline position.
Conclusions:
- Head position asymmetry develops progressively in premature infants, mirroring term infant patterns by 39 weeks.
- The observed head preference is likely influenced by complex interactions of intrinsic fetal factors and the uterine environment.
- Further research is needed to elucidate the specific contributions of prenatal and postnatal experiences to this developing asymmetry.
Abstract:
The head position of 95 infants, born between 30 and 37 weeks gestational age, was observed every 15 min for 2 hr weekly from birth until 39 weeks conceptional age. At 35 weeks and increasingly thereafter, significantly more time was spent with the head to the right than to the left. By 39 weeks the infants were similar to term infants: almost 90% spent 80% or more time with their heads to the right. The increase appeared independent of intra- or extrauterine experience; neither age at birth nor time since birth was consistently related to head position. Unlike term infants, prematures were equally likely to turn left as right and have their heads left as right 15 min after release from a midline position. These findings suggest complex determinants of asymmetry including factors intrinsic to the fetus and those contributed by the uterine environment.