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Risk of preterm delivery and small-for-gestational-age births in women with autoimmune disease using biologics before or during pregnancy: a population-based cohort study
  1. Nicole W Tsao1,2,3,
  2. Eric C Sayre3,
  3. Gillian Hanley4,
  4. Mohsen Sadatsafavi1,2,5,
  5. Larry D Lynd1,2,6,
  6. Carlo A Marra7,
  7. Mary A De Vera1,2,3
  1. 1University of British Columbia Faculty of Pharmaceutical Sciences, Vancouver, British Columbia, Canada
  2. 2Collaboration for Outcomes Research and Evaluation, Vancouver, Canada
  3. 3Arthritis Research Canada, Richmond, British Columbia, Canada
  4. 4University of British Columbia Faculty of Medicine, Department of Obstetrics and Gynecology, Vancouver, British Columbia, Canada
  5. 5Centre for Clinical Epidemiology and Evaluation, Vancouver, British Columbia, Canada
  6. 6Centre for Health Evaluation & Outcomes Sciences, Vancouver, Canada
  7. 7Otago School of Pharmacy, Dunedin, New Zealand
  1. Correspondence to Dr Mary A De Vera, Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada; mdevera{at}


Objectives To assess the risk of preterm delivery and small-for-gestational-age (SGA) births in women with autoimmune diseases using biologics before or during pregnancy.

Methods Using population-based administrative data in British Columbia, Canada, women with one or more autoimmune diseases who had pregnancies between 1 January 2002 and 31 December 2012 were included. Exposure to biologics was defined as having at least one biologic prescription 3 months before or during pregnancy. Each exposed pregnancy was matched with five unexposed pregnancies using high-dimensional propensity scores (HDPS). Logistic regression modelling was used to evaluate the association between biologics use and preterm delivery and SGA.

Results There were 6218 women with 8607 pregnancies who had an autoimmune disease diagnosis; of which 109 women with 120 pregnancies were exposed to biologics 3 months before or during pregnancy. In unadjusted analyses, the ORs for the association of biologics exposure with preterm deliveries were 1.64 (95% CI 1.02 to 2.63) and 1.34 (95% CI 0.72 to 2.51) for SGA. After HDPS matching with 600 unexposed pregnancies, the ORs for the association of biologics exposure and preterm deliveries were 1.13 (95% CI 0.67 to 1.90) and 0.91 (95% CI 0.46 to 1.78) for SGA. Sensitivity analyses using HDPS deciles, continuous HDPS covariate or longer exposure window did not result in marked changes in point estimates and CIs.

Conclusions These population-based data suggest that the use of biologics before and during pregnancy is not associated with an increased risk of preterm delivery or SGA births.

  • biologics
  • pregnancy
  • preterm
  • small-for-gestational-age
  • autoimmune disease

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  • Handling editor Josef S Smolen

  • Contributors NWT: had full access to all the data used in this study and takes responsibility for the integrity of the data and accuracy of data analysis. MADV and NWT: concept and design. MADV, NWT and ECS: acquisition, analysis and interpretation of data. NWT and MADV: drafting of manuscript. NWT, MADV, MS, GH, LDL, CAM: critical revision of manuscript for important intellectual content. NWT and ECS: statistical analysis.

  • Funding This research was funded by an operating grant from The Arthritis Society (YIO-13-07). MADV obtained funding for this study.

  • Disclaimer All inferences, opinions and conclusions drawn in this manuscript are those of the authors and do not reflect the opinions or policies of the Data Stewards.

  • Competing interests NWT is a PhD Candidate and Canadian Institutes of Health Research Fellowship holder. ECS is a biostatistician with Arthritis Research Canada. GH is an Assistant Professor, Canadian Institutes of Health Research New Investigator, and a recipient of Canadian Cancer Society Research Institute Capacity Development Award. MS is an Assistant Professor, Canadian Institutes of Health Research New Investigator, and a Michael Smith Foundation for Health Research Scholar. LDL is a Professor, and Director of Collaboration for Outcomes Research and Evaluation. CAM is a Professor and Dean at the Otago School of Pharmacy, New Zealand. MADV is an Assistant Professor, Canada Research Chair in Medication Adherence, Utilization, and Outcomes, The Arthritis Society Network Scholar, and Michael Smith Foundation for Health Research Scholar. LDL has received honoraria from Boehringer Ingelheim and Pfizer Canada for consulting services unrelated to this study.

  • Patient consent Detail has been removed from this case description/these case descriptions to ensure anonymity. The editors and reviewers have seen the detailed information available and are satisfied that the information backs up the case the authors are making.

  • Ethics approval This study was approved by the University of British Columbia, Behavioural Research Ethics Board.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Correction notice This article has been corrected since it published Online First. The afffiliations list for all authors and table 2 have been updated.

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