Long-term neurodevelopmental outcome after moderate neonatal encephalopathy and after post-term birth : two population-based studies

Abstract

Long-term neurodevelopmental outcome in two population-based groups of children with different perinatal events was studied: A) Children born at term with moderate neonatal encephalopathy (NE) and B) children born post-term , i.e., at a gestational age of > 42 weeks.

Aims: A) To study the long-term neurodevelopmental outcome including cognitive functioning after moderate NE and to investigate white matter regions. B) To evaluate developmental data obtained at the ages of 4 and 5.5 years in children born post-term.

Material and methods: A) Of all children born in Sweden in 1985, 684 had an Apgar score of < 7 at 5 minutes of age. From the records for these children, those with moderate NE were identified, and the obstetric records were evaluated. The mothers of the children not suffering from cerebral palsy (CP) were interviewed semistructured and according to rating scales to obtain information about their child's development and cognitive functioning, and a subgroup was investigated with Diffusion tensor imaging (DTI) and by performing cognitive tests. B) Records from the Child Health Centres for the 354 children who were born after 42 weeks gestation in 1991 at Huddinge University Hospital were assessed to extract the developmental data from each child's check-up at 4 and 5.5 years.

Results: A) Fiftysix children had had moderate NE (0.57/1000). Most pregnancies were found to be uneventful, but post-term deliveries occured significantly more often among the mothers giving birth to children with moderate NE than in the general population (19% vs 8%). Ominous FHR patterns were common in these cases. Fifteen of the 56 children had CP or other major neuroimpairments. Of the 41 without CP, 13 did not participate. Of the 28 children without CP, 20 had cognitive dysfunctions, including learning disabilities, impaired social interaction and executive dysfunctions, and 8 had no impairments. DTI, performed in 9 subjects revealed white matter changes in several regions, including the internal capsules, corpus callosum and frontal white matter areas. B) Definite or suspected neurological disorders/developmental deviations were significantly more common amongst the children born after prolonged pregnancies (13%) than in the comparison group (5.5%).

Conclusions: A) The present study reveals an unexpectantly high rate of cognitive and neurological disbilities/dysfunctions in term children who have suffered from moderate NE. Of all children participating only 19% had no disabilities or dysfunctions. Changes in the DTI were observed in several white matter regions, even in the absence of CP. B) Post-term pregnancies were associated with a higher than average rate of neurological disorders or developmental deviations at the age of 4 and/or 5.5 years.