RT Journal
A1 Hviid A
T1 MAjor birth defects after exposure to newer-generation antiepileptic drugs—reply
JF JAMA
JO JAMA
YR 2011
FD August 24
VO 306
IS 8
SP 826
OP 827
DO 10.1001/jama.2011.1186
UL http://dx.doi.org/10.1001/jama.2011.1186
AB 
Merry et al suggest the study was underpowered to detect an increased birth defect risk associated with the use of newer-generation antiepileptic drugs. The actual statistical power of the study can be evaluated from the 95% confidence intervals of the effect measures. The study showed that birth defect risk increases exceeding 36% are unlikely.