Changes in the birth prevalence of selected birth defects after grain fortification with folic acid in the United States: findings from a multi-state population-based study.
BACKGROUND
Observational studies and clinical trials have suggested that periconceptional use of folic acid can reduce the risk of birth defects other than neural tube defects (NTDs). Using data reported by states to the National Birth Defects Prevention Network, we examined whether folic acid fortification might have decreased the prevalence of other specific birth defects.


METHODS
For each of 16 birth defect categories selected for study, birth prevalence for two time periods was calculated with data submitted from a number of states in 1995-1996 ("pre-fortification") and 1999-2000 ("post-fortification"). Changes in birth prevalence between the two time periods were assessed by calculating prevalence ratios and 95% confidence intervals for each defect, and compared by maternal race/ethnicity and availability of prenatally diagnosed cases.


RESULTS
We confirmed previously reported reductions in the birth prevalence of NTDs. In addition, we found modest, yet statistically significant, decreases in the birth prevalence for transposition of the great arteries(12%), cleft palate only (12%), pyloric stenosis (5%), upper limb reduction defects (11%), and omphalocele (21%). More substantial subgroup decreases were observed for renal agenesis among programs that conduct prenatal surveillance (28%), for common truncus among Hispanics (45%), and for upper limb reduction defects among Hispanics (44%). There were modest yet significant increases in the prevalence of obstructive genitourinary defects (12%) and Down syndrome (7%), but not among programs conducting prenatal surveillance for these defects.


CONCLUSIONS
These results suggest some modest benefit from the folic acid fortification on the prevalence of a number of non-NTD birth defects.
Canfield
Mark A
MA
Birth Defects Epidemiology and Surveillance Branch, Texas Department of State Health Services, Austin, 78756, USA. mark.canfield@dshs.state.tx.us
Collins
Julianne S
JS
Botto
Lorenzo D
LD
Williams
Laura J
LJ
Mai
Cara T
CT
Kirby
Russell S
RS
Pearson
Kay
K
Devine
Owen
O
Mulinare
Joe
J
D000013:Congenital Abnormalities / Q000175:diagnosis* / Q000453:epidemiology*; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000627:therapeutic use*; D005527:Food, Fortified; D006801:Humans; D009436:Neural Tube Defects / Q000517:prevention & control; D011159:Population Surveillance; D011247:Pregnancy; D011295:Prenatal Care; D015995:Prevalence; D013997:Time Factors; D014481:United States
D005492:Folic Acid