Exposure to systemic antibacterial medications during pregnancy and risk of childhood cancer.
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.
['Momen|Natalie C|NC|', 'Olsen|Jørn|J|', 'Gissler|Mika|M|', 'Kieler|Helle|H|', 'Haglund|Bengt|B|', 'Li|Jiong|J|']
D000293:Adolescent D000328:Adult D017668:Age of Onset D000900:Anti-Bacterial Agents D002648:Child D002675:Child, Preschool D003718:Denmark D011307:Drug Prescriptions D005260:Female D006801:Humans D007223:Infant D007231:Infant, Newborn D008297:Male D018811:Maternal Exposure D008875:Middle Aged D009369:Neoplasms D017891:Pharmacoepidemiology D011247:Pregnancy D011297:Prenatal Exposure Delayed Effects D012042:Registries D018570:Risk Assessment D012307:Risk Factors D013548:Sweden D055815:Young Adult
systemic antibacterials pregnancy childhood cancer pharmacoepidemiology register-based epidemiology