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Based on the provided medical research paper, here is a comprehensive breakdown of the data, key trends, and statistical insights regarding the epidemiology of Cerebral Palsy (CP) in western Sweden.
1. Study Profile & Overview
Authors & Publication: Kate Himmelmann, Magnus Påhlman (Published: May 29, 2026).
Study Design: Population-based longitudinal study.
Study Area: Western Sweden (Counties of Västra Götaland, Jönköping, and Halland; ~2.5 million inhabitants).
Focus Cohort (Birth Years 2015–2018): 108,963 live births yielding 194 diagnosed CP cases.
Pre- or peri/neonatal background: 180 children.
Post-neonatal cause: 14 children.
Comparison Cohorts: 1999–2002, 2003–2006, 2007–2010, and 2011–2014.
2. Prevalence Data & Trends
Crude Prevalence Decline
The overall crude prevalence of CP in western Sweden has significantly decreased over the last two decades ($p = 0.01$).
1999–2002 Cohort: 2.18 per 1,000 live births.
2015–2018 Cohort: 1.78 per 1,000 live births (comprising 1.092 in term births and 0.688 in preterm births).
Gestational Age-Specific Prevalence (2015–2018)
Extremely Preterm (< 28 weeks): 65.9 per 1,000 live births (Note: 78.6 per 1,000 neonatal survivors, down from 87.1 in the previous cohort).
Very Preterm (28–31 weeks): 41.5 per 1,000 live births.
Moderately Preterm (32–36 weeks): 5.6 per 1,000 live births.
Term (> 36 weeks): 1.06 per 1,000 live births.
Birth Weight-Specific Prevalence (2015–2018)
< 1,000g: 62.0 per 1,000 live births.
1,000–1,499g: 34.0 per 1,000 live births.
1,500–2,499g: 11.0 per 1,000 live births.
≥ 2,500g: 1.0 per 1,000 live births.
3. Clinical Classifications & CP Subtypes
Among the 180 children with pre-, peri-, or neonatal onset, the distribution of CP types demonstrates that unilateral forms are currently dominating:
| CP Type (Swedish Classification) | SCPE Classification Equivalent | Percentage Share (n=180) |
| Hemiplegia | Unilateral Spastic CP | 51.7% (93 children) |
| Diplegia | Bilateral Spastic CP | 30.6% (55 children) |
| Tetraplegia | Bilateral Spastic CP | 5.6% (10 children) |
| Dyskinetic CP | Dyskinetic CP | 10.6% (19 children) |
| Ataxia | Ataxic CP | 1.7% (3 children) |
Key Takeaway on Spastic CP: Of the 65 children with bilateral spastic CP, the majority (39 children) were born preterm. Conversely, the vast majority of children presenting with unilateral spastic CP (hemiplegia) were born at term.
4. Neuroimaging Findings (MRI)
Information was available for 97% of the cohort. Magnetic Resonance Imaging (MRI) results on 174 children revealed a highly significant shift in brain lesion patterns:
White Matter Lesions: 53.4% (93 children) — The proportion of white matter lesions significantly increased from the 1999–2002 cohort to the 2015–2018 cohort in both preterm ($p=0.001$) and term ($p=0.004$) infants.
Cortical/Subcortical (Grey Matter) Lesions: 18.4% (32 children).
Basal Ganglia/Thalamus Lesions: 10.9% (19 children).
Maldevelopments: 7.5% (13 children).
Normal Findings: 5.2% (9 children).
Other Abnormalities: 4.6% (8 children).
5. Aetiological Periods & Risk Factors
The timing and underlying causes of the brain injuries were categorized into three distinct periods:
Prenatal Origin (34.4% / 62 children)
Dominating causes were periventricular lesions followed by cerebral maldevelopments.
Children with a prenatal background displayed a milder motor impairment overall compared to those with peri- or neonatal onset ($p = 0.04$).
Perinatal/Neonatal Origin (49.4% / 89 children)
Preterm children: Main cause was cerebral hemorrhage.
Term children: Main causes were cerebral infarctions or Hypoxic-Ischaemic Encephalopathy (HIE).
17 children sustained HIE, 10 of whom met the strict ACOG criteria for severe intra-partum hypoxia, and 10 underwent therapeutic hypothermia.
Unclassifiable Period (16.1% / 29 children)
Cases where explicit timing criteria could not be met. 21 of these 29 children were born preterm. The primary reason for missing classifications was a lack of early neonatal ultrasound data to cleanly differentiate prenatal from perinatal white matter damage.
6. Motor Function Outcomes (GMFCS Trends)
Gross motor function was measured via the Gross Motor Function Classification System (GMFCS), where Levels I–II indicate independent walking and Levels IV–V mean wheelchair reliance.
Improved Mobility: 72% of children in the 2015–2018 cohort are able to walk independently (GMFCS I–II), up from 64% in the previous 4-year cohort.
Decrease in Severity: A continuous, statistically significant decline in severe motor impairment (GMFCS IV–V) from 1999 to 2018 was verified in:
Children born at term ($p = 0.03$).
Children born extremely preterm ($p = 0.03$).
Aetiological Correlation: Children with a peri- or neonatal background showed a clear positive trend toward milder motor impairment over the 20-year span ($p = 0.02$ for preterm, $p = 0.01$ for term). No such improvement over time was found in the prenatal or unclassifiable cohorts.
7. Post-Neonatal Cases (Atypical Catchment)
14 children developed CP from events occurring after the first 28 days of life (up to 2 years of age):
Causes: Trauma (5), severe infection (3), hydrocephalus (1), stroke (1), and cardiac arrest (4 — resulting from aspiration, SIDS-like episodes, adverse pharmacological events, and cardiac surgery).
Severity: Highly polarized; while hemiplegia cases skewed toward milder presentation (GMFCS I), all 4 tetraplegia cases and all 3 dyskinetic cases resulting from post-neonatal events were classified at the most severe level (GMFCS V).
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