title: Folic acid fortification and prevalences of neural tube defects, orofacial clefts, and gastroschisis in California, 1989 to 2010.
abstract: BACKGROUND
  We examined whether prevalences of neural tube defects (NTDs), orofacial clefts, and gastroschisis changed more rapidly after than before folic acid fortification in California.
  
  
  METHODS
  This population-based study used vital statistics and birth defects registry data. The study population included all live births and stillbirths delivered in central California counties from 1989 to 2010. Cases included deliveries with NTDs, orofacial clefts, and gastroschisis. Weighted least squares regression was used to estimate slopes during prefortification (before 1997) and postfortification (after 1998), respectively. The difference of the two slopes with the 95% confidence interval (CI) was calculated.
  
  
  RESULTS
  For all NTDs combined, slopes indicated that NTD prevalence was decreasing by 8.7 (slope: -8.7; 95% CI, -13.5--3.9) cases per 100,000 deliveries per year before fortification and by 1.7 (slope: -1.7; 95% CI, -3.7-0.3) after fortification; thus the decline had slowed by 7.0 (95% CI, 2.7-11.3) cases per 100,000 deliveries per year. For orofacial clefts, slopes for cleft lip with/without palate as well as for cleft palate alone indicated that the postfortification slope was lower than the prefortification slope suggesting a more accelerated decrease in the postfortification time period. For gastroschisis, the slope after fortification was lower compared with prefortification, indicating a less accelerated prevalence increase in the postfortification time period. Stratification by race/ethnicity did not substantially alter results.
  
  
  CONCLUSIONS
  We observed a slower decline in prevalence of NTDs, an emergence of a decline in orofacial clefts, and a slower increase in gastroschisis, during the postfortification period in central California, relative to the prefortification period. Birth Defects Research (Part A), 2016. © 2016 Wiley Periodicals, Inc. Birth Defects Research (Part A) 106:1032-1041, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Pediatrics, Division of Neonatology, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Yang
authors.affiliation: Department of Pediatrics, Division of Neonatology, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Suzan L
authors.initials: SL
authors.lastname: Carmichael
authors.affiliation: Department of Pediatrics, Division of Neonatology, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Gary M
authors.initials: GM
authors.lastname: Shaw
mesh_terms: D002140:California / Q000453:epidemiology; D002971:Cleft Lip / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology; D002972:Cleft Palate / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D005527:Food, Fortified; D020139:Gastroschisis / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology; D006801:Humans; D050498:Live Birth / Q000453:epidemiology; D008297:Male; D009436:Neural Tube Defects / Q000175:diagnosis / Q000453:epidemiology* / Q000473:pathology; D011247:Pregnancy; D015995:Prevalence; D012042:Registries; D012044:Regression Analysis; D050497:Stillbirth / Q000453:epidemiology
chemical_list: D005492:Folic Acid
keywords: folic acid; food; food supply; fortified; gastroschisis; neural tube defects; orofacial clefts; pregnancy