TOPLINE:

Despite increased survival rates among infants born extremely preterm at 22-26 weeks of gestation, neurodevelopmental outcomes at the age of 2-2.5 years did not improve in those born between 2014 and 2016 compared with those born between 2004 and 2007.

METHODOLOGY:

• Researchers conducted a population-based cohort study comparing 1062 live births at 22-26 weeks of gestation in Sweden across two distinct 3-year periods: 455 births between 2004 and 2007 (cohort 1) and 607 births between 2014 and 2016 (cohort 2).
• The primary outcome was neurodevelopmental impairment (NDI), defined as the presence of cerebral palsy (CP), vision/hearing impairments, or deficits in cognitive, language, or motor function.
• Using Bayley Scales of Infant and Toddler Development, Third Edition (Bayley III) scores, NDI was classified as none (≥ -1 SD), mild (< -1 SD to ≥ -2 SD), moderate (< -2 SD to ≥ -3 SD), or severe (< -3 SD).
• Neurodevelopmental evaluations for survivors in cohort 1 were performed at 2.5 years of corrected age, and survivors in cohort 2 underwent clinical, physiotherapeutic, and psychological assessments at the age of 2-2.5 years.

TAKEAWAY:

• The overall prevalence of moderate-severe NDI did not differ significantly between the two cohorts (27% vs 35%; adjusted odds ratio [aOR], 1.2; 95% CI, 0.94-1.6).
• Infants born between 2014 and 2016 had higher odds of moderate-severe cognitive impairment (aOR, 1.4; 95% CI, 1.1-2.6) and language impairment (aOR, 2.5; 95% CI, 1.4-4.2) than those born between 2004 and 2007.
• A non-Nordic maternal origin showed strong associations with increased risks for cognitive impairment (aOR, 2.8; 95% CI, 1.4-5.4) and language impairment (aOR, 4.4; 95% CI, 2.4-8.4) among infants born between 2014 and 2016; however, these associations were not observed among those born between 2004 and 2007.
• Overall rates of moderate-severe CP and vision or hearing impairments were comparable between the two cohorts.

IN PRACTICE:

"Future research should continue to focus on identifying the underlying factors driving neurodevelopmental trends, ultimately guiding evidence-based improvements in long-term outcomes," the authors wrote.

SOURCE:

This study was led by Ulrika Ådén, Woman and Child Health, Karolinska Institute, Stockholm, Sweden. It was published online on October 15, 2025, in Archives of Disease in Childhood: Fetal and Neonatal Edition.

LIMITATIONS:

The lower proportion of children in the 2014-2016 cohort, assessed using Bayley III, than those in the 2004-2007 cohort required greater reliance on clinical evaluations for NDI classification. The 2004-2007 cohort was evaluated in a controlled research setting; however, the other cohort relied on clinical assessments with multiple assessors and limited test capacity, which may have introduced variability in Bayley III assessments. The use of a historical control group as a reference could have led to an overestimation of moderate-severe NDI in the cohort of infants born between 2014 and 2016.

DISCLOSURES:

Two authors were supported by grants from the Swedish Research Council, and one author received support through a regional agreement on clinical research between Region Stockholm and Karolinska Institute. The authors declared having no competing interests.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.