Almost three-quarters of children born extremely preterm showed mild or no neurodevelopmental disability at age 2.5 years, according to a population-based study published in the May 1 issue of JAMA.
In comparison, 78% of control subjects born at term showed no neurodevelopmental disability.
"Improved survival did not translate into increasing disability rates, and we, like others, believe that the neurodevelopmental outcome for extremely preterm children born in the 2000s will be better than for those born in the 1990s," said Dr. Fredrik Serenius of the department of women’s and children’s health, Uppsala University, and his associates in the Extremely Preterm Infants Study in Sweden (EXPRESS).
The investigators noted that their results may not be generalizable to other countries. Sweden has "a rather uniform society without extreme poverty. Antenatal care is easily accessible and utilized by close to 100% of mothers. All citizens are covered by general health insurance including a total of 480 days of parental leave after the child’s birth and additional benefits for severely sick children," they said.
EXPRESS is a national prospective study of all infants born in Sweden before 27 weeks’ gestation during 2004-2007. For this study, Dr. Serenius and his colleagues assessed neurological and developmental outcomes in 456 of these children who survived to 2.5 years of corrected age, as well as in 701 control children matched for residence, sex, day of birth, and mother’s country of origin.
Certified psychologists assessed the children’s cognitive, language, and motor development using the Bayley Scales of Infant and Toddler Development. In addition, specialists in pediatrics or pediatric neurology examined the preterm group for neuromotor function. Parents of children in both study groups were interviewed to ascertain parental education level and overall child health and development.
Among the preterm infants, 42% were neurodevelopmentally normal and 31% were mildly disabled. The remaining 27% were moderately or severely disabled, including four children who were blind and one who was blind and deaf. Seven percent of the preterm group had cerebral palsy – 13 with mild CP, 13 with moderate CP, and 6 with severe CP, the investigators said (JAMA 2013;309:1810-20).
In comparison, 78% of children in the control group were neurodevelopmentally normal and another 19% were mildly disabled. The remaining 3% were moderately or severely disabled, including one with severe CP.
The mean composite cognitive score for children in the preterm group was 94, compared with 104 for the control group. The mean composite language scores were 98 and 109, respectively, and the mean composite motor scores were 94 and 107, respectively.
In the preterm group, these scores rose with increasing gestational age at birth, so that cognitive scores were 2.5 points higher for every additional week of gestational age, language scores were 3.6 points higher for every additional week, and motor scores were 2.5 points higher for every additional week.
Overall, even though prematurity had a "large" impact on neurodevelopmental outcomes, most extremely preterm children emerged with no or only mild disability.
"These results are relevant for clinicians counseling families facing extremely preterm birth," Dr. Serenius and his associates said.
This study was supported in part by the Swedish Research Council. No financial conflicts of interest were reported.