title: Exposure to systemic antibacterial medications during pregnancy and risk of childhood cancer.
abstract: BACKGROUND
  Up to one-third of women receive prescriptions for systemic antibacterial medications during pregnancy. This paper looks at the association between maternal use of systemic antibacterial medications during pregnancy and childhood cancer risk in the offspring using the prospective data on medication.
  
  
  METHODS
  A population-based follow-up study was carried out using Danish and Swedish register data. Exposure was maternal redemption of a prescription for a systemic antibacterial in the 3 months prior to pregnancy and during pregnancy (exposure window) documented in the national prescription registers, and offspring were followed up from birth to a cancer diagnosis, death, emigration, day before 15th birthday or end of follow-up, whichever came first. Timing, dosage, specific medication types and types of childhood cancer were also considered.
  
  
  RESULTS
  Mothers of 35.1% (n = 506,194) of the children filled at least one prescription for systemic antibacterials during the exposure window. Exposed children had a hazard ratio of 1.08 (95% confidence interval: 0.97, 1.20) compared with unexposed children. Statistically significant results were found for some specific medications (for example, 'other antibacterials'/Anatomical Therapeutic Chemical code J01X) and combinations of cancer types and specific medications (leukaemia and other antibacterials, and hepatic cancers and tetracyclines).
  
  
  CONCLUSIONS
  The results of this study indicate that most antibacterial drugs used during pregnancy were not related to childhood cancer risk in the offspring. However, some may be associated with the development of some specific types of childhood cancers. Our findings need to be replicated in an independent data source.
authors.affiliation: Section for Epidemiology, Department of Public Health, Aarhus University, Denmark.
authors.forename: Natalie C
authors.initials: NC
authors.lastname: Momen
authors.affiliation: Section for Epidemiology, Department of Public Health, Aarhus University, Denmark.|Department of Epidemiology, University of California, Los Angeles, CA, USA.
authors.forename: Jørn
authors.initials: J
authors.lastname: Olsen
authors.affiliation: THL National Institute for Health and Welfare, Helsinki, Finland.|Nordic School of Public Health NHV, Gothenburg, Sweden.
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.affiliation: Centre for Pharmacoepidemiology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Helle
authors.initials: H
authors.lastname: Kieler
authors.affiliation: Centre for Pharmacoepidemiology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Bengt
authors.initials: B
authors.lastname: Haglund
authors.affiliation: Section for Epidemiology, Department of Public Health, Aarhus University, Denmark.
authors.forename: Jiong
authors.initials: J
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D003718:Denmark / Q000453:epidemiology; D011307:Drug Prescriptions; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects*; D008875:Middle Aged; D009369:Neoplasms / Q000139:chemically induced* / Q000175:diagnosis / Q000453:epidemiology; D017891:Pharmacoepidemiology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents
keywords: childhood cancer; pharmacoepidemiology; pregnancy; register-based epidemiology; systemic antibacterials