Antiepileptic drugs prescribed in pregnancy and prevalence of major congenital malformations: comparative prevalence studies

Abstract

Objective

The aim of this study was to examine the prevalence of major congenital malformations associated with antiepileptic drug (AED) treatment in pregnancy.

Patients and methods

Using data from The Health Improvement Network, we identified women who have given live birth and their offspring. Four subgroups were selected based on the AED treatment in early pregnancy, valproate, carbamazepine, lamotrigine and women not receiving AED treatment. We compared the prevalence of major congenital malformations within children of these four groups and estimated prevalence ratios (PRs) using Poisson regression adjusted for maternal age, sex of child, quintiles of Townsend deprivation score and indication for treatment.

Results

In total, 240,071 women were included in the study. A total of 229 women were prescribed valproate in pregnancy, 357 were prescribed lamotrigine and 334 were prescribed carbamazepine and 239,151 women were not prescribed AEDs. Fifteen out of 229 (6.6%) women prescribed valproate gave birth to a child with a major congenital malformation. The figures for lamotrigine, carbamazepine and women not prescribed AEDs were 2.7%, 3.3% and 2.2%, respectively. The prevalence of major congenital malformation was similar for women prescribed lamotrigine or carbamazepine compared to women with no AED treatment in pregnancy. For women prescribed valproate in polytherapy, the prevalence was fourfold higher. After adjustments, the effect of estimates attenuated, but the prevalence remained two- to threefold higher in women prescribed valproate.

Conclusion

The results of our study suggest that lamotrigine and carbamazepine are safer treatment options than valproate in pregnancy and should be considered as alternative treatment options for women of childbearing potential and in pregnancy.

Keywords:

• pregnancy
• valproate
• lamotrigine
• carbamazepine
• adverse drug effects

Supplementary material

Table S1 The 50 most commonly recorded Read codes for major congenital malformations

Acknowledgments

The study was funded by National Institute for Health Research Health Technology Assessment program (Grant 11/35/06). The funder had no role in the design or conduct of the study. We thank the four women who formed a Lived Experience Advisory Panel for their feedback and input on the study.

Disclosure

PJC has in the last three years been a paid member of an advisory boards of Lundbeck. CJS has received funding for research from Novartis Vaccines and Diagnostics. IP supervises a PhD student who is sponsored by Novo Nordisk. IN is currently member of the NIHR HTA commissioning board. The other authors report no conflicts of interest in this work.