title: Maternal caffeine intake during pregnancy and risk of fetal growth restriction: a large prospective observational study.
abstract: OBJECTIVE
  To examine the association of maternal caffeine intake with fetal growth restriction.
  
  
  METHODS
  Prospective longitudinal observational study.
  
  
  METHODS
  Two large UK hospital maternity units.
  
  
  METHODS
  2635 low risk pregnant women recruited between 8-12 weeks of pregnancy. Investigations Quantification of total caffeine intake from 4 weeks before conception and throughout pregnancy was undertaken with a validated caffeine assessment tool. Caffeine half life (proxy for clearance) was determined by measuring caffeine in saliva after a caffeine challenge. Smoking and alcohol were assessed by self reported status and by measuring salivary cotinine concentrations.
  
  
  METHODS
  Fetal growth restriction, as defined by customised birth weight centile, adjusted for alcohol intake and salivary cotinine concentrations.
  
  
  RESULTS
  Caffeine consumption throughout pregnancy was associated with an increased risk of fetal growth restriction (odds ratios 1.2 (95% CI 0.9 to 1.6) for 100-199 mg/day, 1.5 (1.1 to 2.1) for 200-299 mg/day, and 1.4 (1.0 to 2.0) for >300 mg/day compared with <100 mg/day; test for trend P<0.001). Mean caffeine consumption decreased in the first trimester and increased in the third. The association between caffeine and fetal growth restriction was stronger in women with a faster compared to a slower caffeine clearance (test for interaction, P=0.06).
  
  
  CONCLUSIONS
  Caffeine consumption during pregnancy was associated with an increased risk of fetal growth restriction and this association continued throughout pregnancy. Sensible advice would be to reduce caffeine intake before conception and throughout pregnancy.
mesh_terms: D000293:Adolescent; D000328:Adult; D001724:Birth Weight; D002110:Caffeine / Q000009:adverse effects*; D003367:Cotinine / Q000032:analysis; D005260:Female; D005317:Fetal Growth Retardation / Q000209:etiology*; D005865:Gestational Age; D006801:Humans; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011256:Pregnancy Outcome; D011446:Prospective Studies; D012307:Risk Factors; D012463:Saliva / Q000737:chemistry
chemical_list: D002110:Caffeine; D003367:Cotinine