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Study provides best data yet on developmental problems in extremely premature infants

August 26, 2013 – Researchers from Ottawa, Canada, have pooled data from more than 700 children who were born extremely prematurely to come up with the best estimate yet for the risk of certain developmental problems in this group. The research is published in JAMA Pediatrics by Dr. Gregory Moore and colleagues from the Ottawa Hospital Research Institute (OHRI), the Children’s Hospital of Eastern Ontario Research Institute (CHEO RI) and the University of Ottawa.

The researchers found that between 14 and 31 per cent of infants born between 22 and 25 weeks’ gestation had severe developmental problems at age four to eight, defined as having at least one of the following characteristics: an IQ more than three standard deviations below the mean, cerebral palsy without the ability to walk independently, no useful vision, or no useful hearing. There was no statistically significant difference in the percentage of children having severe developmental problems whether they were born at 22, 23, 24 or 25 weeks gestation, however, there was a statistically significant six per cent decrease in developmental problems with each extra week of gestation when moderate developmental problems were included in the analysis. Overall, the smaller number of surviving children at 22 and 23 weeks’ gestation results in their data being considered less reliable.

“When parents learn that their baby may be born extremely prematurely, some of them want to know what to expect, and we really haven’t been able to give them good answers,” said Dr. Moore, a neonatologist at The Ottawa Hospital and CHEO, and an Assistant Professor at the University of Ottawa. “This new data is not perfect, but the data and discussion about its limitations will give parents a much better picture than they had before of what to expect and consider when making decisions with their physicians and medical team about the care for their baby. Of course, it is important for parents to remember that every baby is different, and it is impossible to predict how one will develop.”

To come up with the new estimates, the researchers conducted a meta-analysis of data from 738 children from nine cohort studies in Europe, Australia, New Zealand, and the United Kingdom, conducted after 2004. All the studies had detailed birth records linked with cognitive testing of the same children between ages four and eight years. Studies from North America were not included because they did not fit the desired high quality criteria.

Reference: Neurodevelopmental Outcomes at 4 to 8 Years of Children Born at 22 to 25 Weeks’ Gestational Age: A Meta-Analysis. Gregory P. Moore, Brigitte Lemyre, Nick Barrowman, Thierry Daboval. JAMA Pediatrics. Published online August 26, 2013.

About the Ottawa Hospital Research Institute
The Ottawa Hospital Research Institute (OHRI) is the research arm of The Ottawa Hospital and is an affiliated institute of the University of Ottawa, closely associated with the university’s Faculties of Medicine and Health Sciences. OHRI includes more than 1,700 scientists, clinical investigators, graduate students, postdoctoral fellows and staff conducting research to improve the understanding, prevention, diagnosis and treatment of human disease.

About the CHEO Research Institute
The CHEO Research Institute coordinates the research activities of the Children’s Hospital of Eastern Ontario (CHEO) and is affiliated with the University of Ottawa. Its three programs of research include molecular biomedicine, health technology, and evidence to practice research; key research themes include cancer, diabetes, obesity, mental health, emergency medicine, musculoskeletal health, electronic health information and privacy, and genetics of rare disease. The CHEO Research Institute makes discoveries today for healthier kids tomorrow. For more information, visit

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