Anecdotal evidence has suggested an association of intravenous drug abuse with alloimmunization; however, published data are limited to case reports.OBJECTIVE:
The purpose of this study was to determine whether women with a history of intravenous drug abuse have an increased risk of alloimmunization.STUDY DESIGN:
A retrospective cohort study was performed with the use of data from a single-center blood bank and perinatal database from 2008–2014. Blood bank data were used to identify women with alloimmunization, which was defined as a positive antibody screen in pregnancy not due to naturally occurring antibodies, agglutinins, autoantibodies, or Rh immunoglobulin administration. Intravenous drug abuse was ascertained from a comprehensive database that has captured all drug abuse in pregnancy since 2008. For women who contributed >1 pregnancy to the database, only the most recent pregnancy was included. The rates of alloimmunization among women with a history of intravenous drug abuse and general obstetric populations were calculated and compared. The distribution of alloantibody types, proportion of Rh-group alloantibodies, and patient Rh status were assessed for intravenous and non–intravenous drug abuse–associated alloimmunization. Characteristics and outcomes between intravenous and non–intravenous drug abuse–associated alloimmunization were assessed for women with clinically significant alloantibodies.RESULTS:
Alloimmunization was more common in women with a history of intravenous drug abuse (11/305 women; 3.6%) compared to women without a history of intravenous drug abuse (288/16,022 women; 1.8%; relative risk, 2.00; 95% confidence interval, 1.11–3.62). Needle-sharing was present in 7 and suspected in 4 women with an intravenous drug abuse history. Among women with a history of intravenous drug abuse, none had a history of transfusion or traditional risk factor for alloimmunization. The distribution of alloantibodies was different between intravenous drug abuse– and non–intravenous drug abuse–associated alloimmunization. Rh group alloantibodies and Rh-negative status were more common in women with a history of intravenous drug abuse. Among Rh-negative women with a history of intravenous drug abuse, 50% of RhD alloimmunization cases occurred in nulliparous women. The rate of multiple alloantibodies was not different between intravenous drug abuse– and non–intravenous drug abuse–associated alloimmunization.CONCLUSION:
Maternal history of intravenous drug abuse is associated with an increased risk of alloimmunization. Approximately 1 in 30 intravenous drug abuse women may be diagnosed with an alloantibody in pregnancy. Given the current US opioid epidemic, increased vigilance in screening is required. Needle-sharing represents a possible mechanism for intravenous drug abuse–associated alloimmunization; however, limited obstetric care, failure to obtain Rh immunoglobulin, or failure to identify early pregnancy loss cannot be excluded.