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

Ann Rheum Dis. 2018 Jun;77(6):869-874. doi: 10.1136/annrheumdis-2018-213023. Epub 2018 Mar 1.


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.

Keywords: autoimmune disease; biologics; pregnancy; preterm; small-for-gestational-age.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Arthritis / drug therapy
  • Arthritis / epidemiology
  • Autoimmune Diseases / drug therapy*
  • Autoimmune Diseases / epidemiology
  • Biological Products / administration & dosage
  • Biological Products / adverse effects*
  • British Columbia / epidemiology
  • Cohort Studies
  • Drug Administration Schedule
  • Drug Utilization / statistics & numerical data
  • Female
  • Gestational Age
  • Humans
  • Infant, Newborn
  • Infant, Small for Gestational Age*
  • Pregnancy
  • Pregnancy Complications / drug therapy*
  • Pregnancy Complications / epidemiology
  • Premature Birth / chemically induced*
  • Premature Birth / epidemiology
  • Prenatal Care / methods
  • Registries
  • Risk Assessment / methods


  • Biological Products