Search

AIM: To investigate reasons for the declining prevalence of cerebral palsy (CP) in children born at term in Denmark by evaluating obstetric and neonatal factors associated with CP, and their changes over time.METHOD: In this cohort study, we included 987 495 children (504 600 [51.1%] males and 482 895 [48.9%] females) born after 37 completed gestational weeks during birth years 1997 to 2013. Risk ratios of CP for each factor were calculated with log-binominal regression analyses. Significant factors were evaluated concerning their development in prevalence over time.RESULTS: In the antenatal period, there were significant associations with an increased risk of CP and high maternal body mass index (BMI), smoking during pregnancy, nulliparity, male sex, gestational age, and low birthweight. In the study period, fewer females smoked during pregnancy and fewer children were born post-term, dropping from 22.6% to 11.4% and 9.4% to 2.5% respectively. Conversely, the proportion of females with high BMI increased. Most significant risk factors were found in the neonatal period, with an increase in children with diagnosed birth defects and children admitted to neonatal care.INTERPRETATION: Reasons for the declining prevalence of CP appear to be multifactorial and likely include the decline in maternal smoking and children born post-term along with centralization and advances in neonatal treatment.

Preterm infants have an increased risk of neurodevelopmental disorders. We established a direct quantitative comparison of the association between the degree of prematurity and three different neurodevelopmental disorders.In this cohort study, we combined data from 995,498 children in the Danish Medical Birth Register, from birth years 1997-2013, with information on cerebral palsy, epilepsy, and special educational needs. We estimated the gestational week-specific prevalence and risk for each of the disorders.The risk ratio of cerebral palsy at gestational weeks 21-24, compared to term birth, was more than ten times higher than for the two other disorders. The prevalence of epilepsy and special educational needs declined almost parallel, with 9.2% (4.6%-13.5%) and 12.5% (11.2%-13.7%), respectively, per week of gestation toward term birth. Cerebral palsy did not decline similarly: from gestational weeks 21-24 until week 29 the prevalence declined insignificantly by 0.6% (-11.1%-11.0%) per week; whereas from week 29 until term, the prevalence declined markedly by 36.7% (25.9%-45.9%) per week.The prevalence and risk of cerebral palsy are affected differently by the degree of prematurity compared with epilepsy and special educational needs, possibly reflecting important differences in cerebral pathophysiology.For each week of gestation toward term birth, there was a clear log-linear decline in the prevalence of early childhood epilepsy and special educational needs. In contrast, the risk of cerebral palsy was high at the earliest gestational age, and the prevalence did not decline significantly until gestational week 29, from where it declined notably by nearly 40% for each week of gestation until term birth. Our results indicate important differences in the pathophysiological processes that associate preterm birth with these three neurodevelopmental disorders.