Neurodevelopmental Disorders Prevalent in Extremely Preterm Birth

A large registry-based cohort study in Sweden has revealed that 75% of children born before 24 weeks of gestation had neurodevelopmental disorders, including intellectual disabilities and autism, and required habilitative services.

In addition, somatic disorders such as asthma and failure to thrive/short stature were diagnosed in 88% of the cohort. The findings, published in Acta Paediatrica, emphasize the need for further study of this population, especially as survival rates continue to increase.

“The primary aim of this large, retrospective, national study was to report clinical diagnoses registered after children born before 24 weeks were discharged from neonatal care,” explained lead author Eva Morsing, MD, PhD, of Lund (Sweden) University, and colleagues.

Data on diagnoses of neurodevelopmental disorders and selected somatic diagnoses were obtained from national Swedish registries. Study participants’ individual medical files were also examined by the researchers.


The study cohort comprised 383 infants born at a median of 23.3 weeks of gestation (range, 21.9-23.9 weeks). The median birthweight of participants was 565 grams (range, 340-874 grams), with a median birthweight standard deviation (SD) of −0.40 (range, −3.63–3.17).

The majority (75%) of infants had a neurodevelopmental disorder, including speech disorders (52%), intellectual disabilities (40%), attention-deficit/hyperactivity disorder (30%), autism spectrum disorder (24%), visual impairment (22%), cerebral palsy (17%), epilepsy (10%), and hearing impairment (5%).

With respect to gender, a greater number of boys than girls born at 23 weeks had intellectual disabilities (45% vs. 27%; P < .01) and visual impairment (25% vs. 14%; P < .01). Moreover, 55% of the participants were referred for habilitative services.

With respect to somatic diagnoses, failure to thrive/short stature was diagnosed in 39% of the cohort, and it occurred more often in those born at 21 and 22 weeks than in those born at 23 weeks (49% vs. 36%; P < .05).

In addition, asthma and childhood bronchopulmonary dysplasia, pulmonary hypertension, and vocal cord paresis were diagnosed in 63%, 12%, and 13% of participants, respectively.

“Several studies have reported higher rates of preterm morbidities, and poor neurodevelopmental outcomes after extremely preterm birth in boys rather than girls,” study author Ann Hellström, MD, PhD, of the University of Gothenburg, Sweden, said in an interview.

“While the reasons for this were not studied in the present paper, reports in the literature suggest that boys have a higher average growth rate than girls and appear to be more sensitive to suboptimal neonatal nutrition than girls,” Hellström explained.

“We also know that sex steroids differ in relation to intrauterine life depending on the sex after preterm birth,” Hellström added.

In an accompanying editorial, Neil Marlow, MD, of University College London, wrote, “One headline from this study [that is interesting] is the high prevalence of autistic spectrum disorders recorded.

“This is a particular finding in extremely preterm cohorts from Sweden, who record more diagnoses than in other longitudinal studies,” Marlow added. “It certainly warrants further investigation and understanding.”

The researchers acknowledged that a key limitation of the study was the broad age range at the most recent follow-up visit, which ranged from 2 to 13 years, explaining that some diagnoses may occur later in childhood.

“Neonatal clinical practice needs to adopt a long-term perspective and clinicians treating children and adults should be aware of the complicated health problems of children born before 24 weeks,” they concluded.

This study was supported by the Swedish Medical Research Council, the Gothenburg Medical Society, and by grant funding from the Swedish government. The authors reported no relevant disclosures.

This article originally appeared on, part of the Medscape Professional Network.

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