Lacosamide serum concentrations during pregnancy

•This is the first case series on the changes in lacosamide levels in seven women during pregnancy.•Lacosamide dose normalized concentrations had a significant decrease during trimesters 2 and 3.•None of the infants with exposure to lacosamide had significant major congenital malformations.•Lacosamide metabolism increase during pregnancy could result in lower levels and more seizures.