Table 3

Number of events, crude event rates (per 1000), crude IRRs and adjusted HRs for the four outcomes and each of the AEDs studied—study population limited to women considered to be treated for epilepsy

EventsCrude event ratesIRRHR* (95% CI)HR† (95% CI)
Neurodevelopmental disorders
 Lamotrigine324.2
 Carbamazepine‡11.50.4 (0.0 to 2.7)0.2 (0.0 to 2.7)0.2 (0.0 to 2.7)
 Levetiracetam83.70.9 (0.4 to 1.9)0.8 (0.4 to 1.8)0.8 (0.4 to 1.8)
Valproic acid5013.53.2 (2.0 to 5.0)3.2 (2.0 to 4.9)3.5 (2.3 to 5.4)
Pervasive developmental disorders
 Lamotrigine70.9
 Carbamazepine‡00.0N/AN/AN/A
 Levetiracetam41.82.0 (0.6 to 6.8)1.8 (0.5 to 6.6)1.8 (0.5 to 6.6)
Valproic acid174.54.9 (2.0 to 11.8)4.9 (2.0 to 11.8)4.7 (1.9 to 11.4)
Mental retardation
 Lamotrigine101.3
 Carbamazepine‡00.0N/AN/AN/A
 Levetiracetam10.50.3 (0.0 to 2.7)0.4 (0.1 to 2.9)0.4 (0.1 to 2.9)
Valproic acid154.03.0 (1.4 to 6.7)3.1 (1.4 to 7.0)4.0 (1.9 to 8.6)
Visits to a speech therapist
 Lamotrigine12216.2
Carbamazepine‡46.10.4 (0.1 to 1.0)0.2 (0.1 to 0.7)0.2 (0.1 to 0.7)
 Levetiracetam2210.20.6 (0.4 to 1.0)0.7 (0.4 to 1.1)0.7 (0.4 to 1.1)
Valproic acid9325.11.6 (1.2 to 2.0)1.4 (1.1 to 1.8)1.5 (1.1 to 1.9)
  • Lines marked in bold correspond to HRs for which the 95% CI does not include 1.

  • *Adjusted for all covariates except hospitalisation for epilepsy during pregnancy.

  • †Adjusted for all covariates including hospitalisation for epilepsy during pregnancy.

  • ‡No possible adjustment for the proxy for alcohol.

  • AED, antiepileptic drug; CI, confidence interval; HR, hazard ratio; IRR, incidence rate ratio; N/A, not applicable.