title: Folic acid supplementation and interpregnancy interval.
abstract: BACKGROUND
  Maternal folic acid supplementation between subsequent pregnancies may be important to reduce the risk of low folate status associated with short interpregnancy intervals. We examined how the prevalence of preconception folic acid use for a given pregnancy in Norwegian women varied according to the time interval from the previous pregnancy.
  
  
  METHODS
  Analysis was based on 48 855 pairs of pregnancies with the second pregnancy included in the Norwegian Mother and Child Cohort Study (birth years 1999-2009). Interpregnancy interval was defined as the time from birth of a child to the conception of the subsequent sibling. Preconception folic acid use was defined as any use of folic acid-containing supplements within the last 4 weeks before the second pregnancy.
  
  
  RESULTS
  The prevalence of preconception folic acid use was 31%. Among women with a term birth (≥37 weeks) in the previous pregnancy (92%), those with interpregnancy intervals ≤12 and ≥49 months were associated with up to 35% lower prevalence of preconception folic acid use for the second pregnancy, relative to the reference group (13-24 months). The low use in short intervals was mainly attributable to lower proportion of planned pregnancies and fewer women with higher education. Among women with a preterm birth (<37 weeks) in the previous pregnancy (8%), preconception folic acid use significantly decreased with increasing pregnancy spacing.
  
  
  CONCLUSIONS
  Our finding of a lower preconception folic acid use in women with both short and long interpregnancy intervals might help identifying those with higher risk of folate deficiency and preventing unwanted pregnancy outcomes.
authors: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway; Alessandra Lisi International Centre on Birth Defects and Prematurity, Rome, Italy.
authors: Roy Miodini
authors: RM
authors: Nilsen
authors: Pierpaolo
authors: P
authors: Mastroiacovo
authors: Nina
authors: N
authors: Gunnes
authors: Elin R
authors: ER
authors: Alsaker
authors: Anne Lise
authors: AL
authors: Bjørke-Monsen
authors: Simone J P M
authors: SJ
authors: Eussen
authors: Margaretha
authors: M
authors: Haugen
authors: Ane
authors: A
authors: Johannessen
authors: Helle Margrete
authors: HM
authors: Meltzer
authors: Camilla
authors: C
authors: Stoltenberg
authors: Per Magne
authors: PM
authors: Ueland
authors: Stein Emil
authors: SE
authors: Vollset
mesh_terms: D000328:Adult; D001721:Birth Intervals; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D005494:Folic Acid Deficiency / Q000150:complications* / Q000178:diet therapy; D005500:Follow-Up Studies; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009436:Neural Tube Defects / Q000453:epidemiology / Q000517:prevention & control*; D009664:Norway / Q000453:epidemiology; D016742:Preconception Care; D011247:Pregnancy; D047928:Premature Birth; D011446:Prospective Studies; D014815:Vitamins / Q000008:administration & dosage*; D044465:White People
chemical_list: D014815:Vitamins; D005492:Folic Acid
keywords: cohort; folate; interpregnancy interval; pregnancy; vitamins