Antibiotics and oral contraceptive failure — a case-crossover study

Sengwee Toh; Allen A Mitchell; Marlene Anderka; Lolkje T.W de Jong-van den Berg; Sonia Hernández-Díaz; National Birth Defects Prevention Study

doi:10.1016/j.contraception.2010.08.020

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Antibiotics and oral contraceptive failure — a case-crossover study

Journal article

Peer reviewed

Antibiotics and oral contraceptive failure — a case-crossover study

Sengwee Toh, Allen A Mitchell, Marlene Anderka, Lolkje T.W de Jong-van den Berg, Sonia Hernández-Díaz and National Birth Defects Prevention Study

Contraception (Stoneham), Vol.83(5), pp.418-425

2011

DOI: 10.1016/j.contraception.2010.08.020

PMCID: PMC3326585

PMID: 21477683

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Abstract

Evidence on the association between antibiotic use and combined oral contraceptive (COC) failure is controversial. We examined the effect of concomitant antibiotic treatment on the risk of breakthrough pregnancy among COC users. We performed a case-crossover study of 1330 COC failure cases among 17,721 women from the Slone Epidemiology Center Birth Defects Study (1997–2008) and among 25,941 women from the National Birth Defects Prevention Study (NBDPS, 1997–2005). Self-matched odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by comparing antibiotic use between the 4 weeks before conception (“case period”) and the 4–8 weeks before conception (“control period”) using conditional logistic regression. A case–time-control analysis was conducted using nonusers of COCs with unplanned pregnancies as controls. For the combined data, the self-matched OR was 1.08 (95% CI: 0.63–1.84) and the case–time-control OR was 1.12 (0.63–1.98) for antibiotics overall. The results did not appreciably differ when adjusted for characteristics that might vary between the case and control period. However, among COC failure cases from the NBDPS, allowing a 1-month gap between the case and control period resulted in a self-matched OR of 1.45 (0.85–2.50) and a case–time-control OR of 1.55 (0.86–2.79) for antibiotics overall. We did not find an association between concomitant antibiotic use and the risk of breakthrough pregnancy among COC users. However, due to limited power and potential carryover effects, findings from this study cannot rule out an elevated risk of COC failure among antibiotic users.

Antibiotics

Epidemiology

Pregnancy

Case-crossover study

Drug interactions

Oral contraceptives

Details

Title: Subtitle: Antibiotics and oral contraceptive failure — a case-crossover study
Creators: Sengwee Toh - Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA 02215, USA
Allen A Mitchell - Slone Epidemiology Center at Boston University, Boston, MA 02215, USA
Marlene Anderka - The Massachusetts Center for Birth Defects Research and Prevention, Massachusetts Department of Public Health, Boston, MA 02108, USA
Lolkje T.W de Jong-van den Berg - Department of Pharmacoepidemiology and Pharmacoeconomics, Graduate School of SHARE, Groningen University, 9713 AV Groningen, The Netherlands
Sonia Hernández-Díaz - Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA
National Birth Defects Prevention Study
Contributors: Paul A Romitti (Contributor) - University of Iowa, Epidemiology
Resource Type: Journal article
Publication Details: Contraception (Stoneham), Vol.83(5), pp.418-425
DOI: 10.1016/j.contraception.2010.08.020
PMID: 21477683
PMCID: PMC3326585
NLM abbreviation: Contraception
ISSN: 0010-7824
eISSN: 1879-0518
Publisher: Elsevier Inc
Grant note: HD27697 / National Institute of Child Health and Human Development Pfizer Rhone-Poulenc Rorer GlaxoSmithKline Hoechst Marion Roussel Centers for Disease Control and Prevention HL50763 / National Heart, Lung, and Blood Institute Aventis and Sanofi Pasteur
Language: English
Date published: 2011
Academic Unit: Epidemiology; Biostatistics
Record Identifier: 9984214839802771

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