The last two months in the womb are critical for the correct development of the infant brain, say researchers. According to a study presented at the annual meeting of the Society for Neuroscience, the brains of babies born very prematurely do not develop as well as those who are carried to full-term.
Study leader, Dr. Sandra Witelson from McMaster University, said that an ultrasound study of the brains of babies born after only 26 weeks gestation showed that certain aspects of brain development were very compromised compared to infants in utero. "These findings indicate that the normal early maturation of the brain may be compromised when it takes place outside of the womb," said Witelson. "We found that in very premature babies, a part of the brain doesn't show normal growth after birth, and in fact some parts of the brain didn't change at all from the day the babies were born until they reached what would have been a full-term birth date."
The results are based on a study of premature babies born just 26 weeks into a normal 40-week pregnancy. Ultrasounds of the infants' brains were done at birth and again when they were discharged from hospital, generally around 36 weeks since conception. These ultrasounds were then compared to the brain ultrasounds - taken in utero at about 26 weeks gestation and at birth - of full-term infants.
For the premature babies, the ultrasounds showed that frontal portions of the brain were comparable at birth to the brains of babies still in utero at that stage of gestation. However, after about 10 weeks in intensive care, the second measurement of the premature babies' brains showed some portions of the front part of the brain were significantly smaller than those of babies who were born full-term. Most affected were the prefrontal regions of the brain, important for numerous intellectual functions, including attention, planning and social functioning.
Witelson said the findings indicated further research was needed to try to understand what mechanisms in utero are missing after birth that are essential for the normal process of neural development. She added that the results could have relevance as to how premature babies are cared for; as it may be that the early brain may be compromised by being subjected to complex stimulation too early.
Witelson explained that the sensory environment for a premature baby outside the womb was very different to that experienced in utero. In the womb, the eyelids are closed, the infant is bathed in fluid and minimal sounds are audible, so very little patterned sensory stimulation reaches the brain. Once the premature infant is born however, she is necessarily bombarded by a complex environment full of sights, sounds and touches.
"This research suggests that stimulation of the brain while it is still under construction may not be beneficial," Witelson concluded. Suggesting that future research should try and ascertain the optimal conditions and treatment needed to foster brain development for very premature infants in neonatal intensive care units.
Source: McMaster University