Does folic acid use decrease the risk for spina bifida after in utero exposure to valproic acid?
OBJECTIVE
Women with child wish are advised to take folic acid supplements to reduce the risk for spina bifida. However, there is less evidence for this protective effect in women using valproic acid (VPA). We investigated the effect of folic acid in women exposed to VPA in the first trimester of pregnancy.


METHODS
A case-control study was performed with data from a population-based registry of congenital malformations. Our cases were spina bifida registrations and all other malformed registrations (excluding folic acid sensitive malformations) were used as controls.


RESULTS
The ORs for the effect of correct folic acid use were calculated among antiepileptic drug (AED) unexposed pregnancies 0.5 [95%CI: 0.3-0.7] and among VPA exposed pregnancies 1.0 [95%CI: 0.1-7.6].


CONCLUSIONS
Due to power-reasons, we cannot conclude that folic acid has no effect on the risk for spina bifida among VPA exposed pregnancies. Although for AED unexposed pregnancies we found a decreased risk. Results from (animal) studies support a biologically plausible association between VPA, folic acid and spina bifida. While folic acid might not be able to reduce the risk for lower spina bifida lesions caused by VPA, the use of folic acid might be important to reduce the risk for higher, folic acid sensitive spina bifida lesions. Further research is needed to get more insight in the most effective form and dose of FA in women that use VPA to reduce the risk for (higher forms of) spina bifida.
Jentink
Janneke
J
PharmacoEpidemiology & PharmacoEconomics, SHARE, University of Groningen, The Netherlands.
Bakker
Marian K
MK
Nijenhuis
Cynthia M
CM
Wilffert
Bob
B
de Jong-van den Berg
Lolkje T W
LT
D000014:Abnormalities, Drug-Induced / Q000209:etiology / Q000517:prevention & control*; D000927:Anticonvulsants / Q000009:adverse effects* / Q000627:therapeutic use; D016022:Case-Control Studies; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000627:therapeutic use*; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012307:Risk Factors; D016135:Spinal Dysraphism / Q000517:prevention & control*; D014635:Valproic Acid / Q000009:adverse effects* / Q000627:therapeutic use
D000927:Anticonvulsants; D014635:Valproic Acid; D005492:Folic Acid