Birth characteristics and risk of febrile seizures

Abstract

Objective: Febrile seizure is a common childhood disorder that affects 2-5% of all children, and is associated with later development of epilepsy and psychiatric disorders. This study determines how the incidence of febrile seizures correlates with birth characteristics, age, sex and brain development.

Methods: This is a cohort study of all children born Denmark between 1977 and 2011 who were alive at 3 months of age (N = 2,103,232). The Danish National Patient Register was used to identify children with febrile seizures up to 5 years of age. Follow-up ended on 31 December 2016 when all cohort members had potentially reached 5 years of age.

Results: In total, 75,593 (3.59%, 95% CI: 3.57-3.62%) were diagnosed with febrile seizures. Incidence peaked at 16.7 months of age (median: 16.7 months, interquartile range: 12.5-24.0). The 5-year cumulative incidence of febrile seizures increased with decreasing birth weight (<1500 g; 5.42% (95% CI: 4.98-5.88% vs. 3,000-4,000 g; 3.53% (95% CI: 3.50-3.56%)) and with decreasing gestational age at birth (31-32 weeks; 5.90% (95% CI: 5.40-6.44%) vs. 39-40 weeks; 3.56% (95% CI: 3.53-3.60)). Lower gestational age at birth was associated with higher age at onset of a first febrile seizure; an association that essentially disappeared when correcting for age from conception.

Conclusions: The risk of febrile seizures increased with decreasing birth weight and gestational age at birth. The association between low gestational age at birth and age at first febrile seizure suggests that onset of febrile seizures is associated with the stage of brain development.

Keywords: birth weight; brain development; febrile seizures and epilepsy; gestational age.

Figure 1:

Cumulative incidence of first febrile seizure by birth weight (Figure 1a) and by gestational age at birth (Figure 1b) in 2,103,288 children born in Denmark in 1977-2011 with follow up to 31 December 2016.

Figure 1:

Cumulative incidence of first febrile seizure by birth weight (Figure 1a) and by gestational age at birth (Figure 1b) in 2,103,288 children born in Denmark in 1977-2011 with follow up to 31 December 2016.

Figure 2:

Cumulative distribution of age at first febrile seizure, by gestational age at birth in 71,551 children born in Denmark in 1978-2011. Cumulative distribution of age from birth at first febrile seizure by gestational age at birth (Figure 2a). Cumulative distribution of age from conception at first febrile seizure by gestational age at birth (Figure 2b).

Figure 2:

Cumulative distribution of age at first febrile seizure, by gestational age at birth in 71,551 children born in Denmark in 1978-2011. Cumulative distribution of age from birth at first febrile seizure by gestational age at birth (Figure 2a). Cumulative distribution of age from conception at first febrile seizure by gestational age at birth (Figure 2b).