Outcomes in children after mild neonatal hypoxic ischaemic encephalopathy: A population-based cohort study

OBJECTIVE

To investigate whether mild neonatal hypoxic ischaemic encephalopathy (HIE) in term born infants is associated with cerebral palsy, epilepsy, mental retardation and death up to 6 years of age.

DESIGN

Population-based cohort study.

SETTING

Sweden, 2009-2015.

POPULATION

Live term born infants without congenital malformations or chromosomal abnormalities (n = 505 075).

METHODS

Birth and health data were retrieved from Swedish national health and quality registers. Mild HIE was identified by diagnosis in either the Swedish Medical Birth Register or the Swedish Neonatal Quality Register. Cox proportional hazards regression was used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs).

MAIN OUTCOME MEASURES

A composite of the outcomes cerebral palsy, epilepsy, mental retardation and death up to 6 years of age.

RESULTS

Median follow-up time was 3.3 years after birth. Of 414 infants diagnosed with mild HIE, 17 were classified according to the composite outcome and incidence rates were 12.6 and 2.9 per 1000 child-years in infants with and without HIE respectively. Infants with mild HIE was four times as likely to be diagnosed with the composite outcome (HR 4.42, 95% CI 2.75-7.12) compared with infants without HIE. When analysed separately, associations were found with cerebral palsy (HR 21.50, 95% CI 9.59-48.19) and death (HR 19.10, 95% CI 7.90-46.21). HRs remained essentially unchanged after adjustment for covariates.

CONCLUSIONS

Mild neonatal HIE was associated with neurological morbidity and mortality in childhood. Challenges include identifying infants who may develop morbidity and how to prevent adverse outcomes.

Risk factors for seizures in the vigorous term neonate: A population-based register study of singleton births in Sweden

Background

Neonatal seizures have been associated with increased mortality and impaired neurodevelopment and, knowledge about risk factors may be useful for prevention. Clear associations have been established between labor-related risk factors and seizures in asphyxiated neonates. However, there is limited information about why some vigorous term-born infants experience seizures.

Objectives

Our aim was to assess antepartum and intrapartum risk factors for seizures in vigorous term-born neonates.

Methods

This was a national cohort study of singleton infants born at term in Sweden from 2009–2015. Vigorous was defined as an Apgar score of at least 7 at 5 and 10 minutes. Data on the mothers and infants were obtained from the Swedish Medical Birth Register and the Swedish Neonatal Quality Register. A diagnosis of neonatal seizures was the main outcome measure and the exposures were pregnancy and labor variables. Logistic regression analysis was used and the results are expressed as adjusted odds ratios (aOR) with 95% confidence intervals (CI).

Results

The incidence of neonatal seizures was 0.81/1,000 for 656 088 births. Seizures were strongly associated with obstetric emergencies (aOR 4.0, 95% CI 2.2–7.4), intrapartum fever and/or chorioamnionitis (aOR 3.4, 95% CI 2.1–5.3), and intrapartum fetal distress (aOR 3.0, 95% CI 2.4–3.7). Other associated intrapartum factors were: labor dystocia, occiput posterior position, operative vaginal delivery, and Cesarean delivery. Some maternal factors more than doubled the risk: a body mass of more than 40 (aOR 2.6, 95% CI 1.4–4.8), hypertensive disorders (aOR 2.3, 95% CI 1.7–3.1) and diabetes mellitus (aOR 2.6, 95% CI 1.7–4.1).

Conclusion

A number of intrapartum factors were associated with an increased risk of seizures in vigorous term-born neonates. Obstetric emergencies, intrapartum fever and/or chorioamnionitis and fetal distress were the strongest associated risks. The presence of such factors, despite a reassuring Apgar score could prompt close surveillance.