title: Use of macrolides in mother and child and risk of infantile hypertrophic pyloric stenosis: nationwide cohort study.
abstract: OBJECTIVE
  To assess the association between use of macrolide antibiotics in mothers and infants from pregnancy onset until 120 days after birth and infantile hypertrophic pyloric stenosis (IHPS).
  
  
  METHODS
  Nationwide register based cohort study.
  
  
  METHODS
  Denmark, 1996-2011.
  
  
  METHODS
  999,378 liveborn singletons and linked individual level information on macrolide prescriptions (maternal use during pregnancy, n=30,091; maternal use after birth, n=21,557; use in infants, n=6591), surgery for IHPS, and potential confounders.
  
  
  METHODS
  Surgery for IHPS by three categories of macrolide use: in mothers during pregnancy, in mothers after birth, and in infants after birth.
  
  
  RESULTS
  880 infants developed IHPS (0.9 cases per 1000 births). Compared with infants with no use of macrolides, the adjusted rate ratio for IHPS in infants with use of macrolides during days 0 to 13 after birth was 29.8 (95% confidence interval 16.4 to 54.1) and during days 14 to 120 was 3.24 (1.20 to 8.74); the corresponding absolute risk differences were 24.4 (95% confidence interval 13.0 to 44.1) and 0.65 (0.06 to 2.21) cases per 1000 infants exposed to macrolides, respectively. The rate ratio for maternal use of macrolides for days 0 to 13 after birth was 3.49 (1.92 to 6.34) and for days 14 to 120 was 0.70 (0.26 to 1.90); the corresponding absolute risk differences were 2.15 (0.82 to 4.64) and -0.11 (-0.26 to 0.31). The rate ratios for maternal use of macrolides during pregnancy were 1.02 (0.65 to 1.59) for weeks 0 to 27 and 1.77 (0.95 to 3.31) for weeks 28 to birth; the corresponding absolute risk differences were 0.01 (-0.31 to 0.50) and 0.67 (-0.06 to 2.02).
  
  
  CONCLUSIONS
  Treatment of young infants with macrolide antibiotics was strongly associated with IHPS and should therefore only be administered if potential treatment benefits outweigh the risk. Maternal use of macrolides during the first two weeks after birth was also associated with an increased risk of IHPS. A possible association was also found with use during late pregnancy.
authors.affiliation: Department of Epidemiology Research, National Health Surveillance and Research, Statens Serum Institut, Artillerivej 5, 2300 Copenhagen S, Denmark.
authors.forename: Marie
authors.initials: M
authors.lastname: Lund
authors.forename: Björn
authors.initials: B
authors.lastname: Pasternak
authors.forename: Rie B
authors.initials: RB
authors.lastname: Davidsen
authors.forename: Bjarke
authors.initials: B
authors.lastname: Feenstra
authors.forename: Camilla
authors.initials: C
authors.lastname: Krogh
authors.forename: Lars J
authors.initials: LJ
authors.lastname: Diaz
authors.forename: Jan
authors.initials: J
authors.lastname: Wohlfahrt
authors.forename: Mads
authors.initials: M
authors.lastname: Melbye
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000009:adverse effects* / Q000627:therapeutic use; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D018942:Macrolides / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000188:drug therapy; D046248:Pyloric Stenosis, Hypertrophic / Q000139:chemically induced* / Q000453:epidemiology; D012042:Registries; D012307:Risk Factors; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides