Folic acid supplementation and neural tube defect recurrence prevention.
BACKGROUND
It is well established that women who have had a pregnancy affected by a neural tube defect (NTD) have an elevated risk of a subsequent NTD-affected pregnancy and that a high dose (4 mg/day) of folic acid taken around the time of conception prevents most recurrences of NTDs.


METHODS
We reviewed the literature to identify studies that quantify the reduction in risk if women with a prior-NTD affected pregnancy consistently take folic acid before and during a subsequent pregnancy and the effectiveness of NTD recurrence prevention programs in increasing the percentage of women who consistently consume folic acid supplements.


RESULTS
A meta-analysis of randomized trials of folic acid for the prevention of recurrent NTDs indicates a 69% reduction in recurrence risk if analyzed on an intention-to-treat basis and an 87% reduction among those women who took supplements prior to the beginning of pregnancy. Observational studies report reductions in recurrence risk of 85% to 100% among women taking folic acid prior to subsequent pregnancies. The percentage of women who take folic acid prior to a subsequent pregnancy has been reported to vary from 33% to 85%, varying with the demographic background and the intensity of folic acid counseling efforts.


CONCLUSIONS
Targeted folic acid information and counseling provided to women with an NTD-affected pregnancy has been demonstrated to substantially reduce the risk of recurrent NTDs and is feasible to implement on a public health basis.
Grosse
Scott D
SD
National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
Collins
Julianne S
JS
D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D009436:Neural Tube Defects / Q000178:diet therapy / Q000453:epidemiology / Q000517:prevention & control*; D011247:Pregnancy; D011295:Prenatal Care; D016032:Randomized Controlled Trials as Topic; D012008:Recurrence
D005492:Folic Acid