Risk of exposure to blood products during pregnancy: guidance for Zika and other donor deferral policies.

BACKGROUND: Exposure to blood products during pregnancy carries a potential risk of transfusion transmission of infectious agents. Blood agencies have historically sought optimal deferral and testing strategies to protect blood supplies in part to ensure the protection of pregnant women and their unborn infants. The Zika virus outbreak of 2016 has heightened attention to these concerns. In the current context of the recent Zika outbreak, and also more broadly, data are needed to shed light on the likelihood of exposure to blood products throughout pregnancy to inform policy.

STUDY DESIGN AND METHODS: Hospital administrative data from a large tertiary care center were examined for outpatient and nondelivery inpatient transfusion events in pregnant women between January 1, 2007, and December 31, 2013. Those pregnancies resulting in miscarriage were excluded from analysis.

RESULTS: A total of 45,179 pregnancies resulting in delivery of a live or stillborn infant were documented at The Ottawa Hospital during the study period. Our findings indicate that 0.124%, or 1240 in 1,000,000, expectant mothers received transfusion at some point during their pregnancies with 0.04%, or 400 per 1,000,000, expectant mothers receiving a transfusion in the first trimester.

CONCLUSION: Data from a large tertiary care center suggest that the risk of maternal and fetal exposure to blood products by transfusion during any stage of pregnancy is very low. Such a low likelihood of transfusion should be taken into consideration when developing donor deferral policies designed to protect women against transfusion-associated infection transmission during pregnancy and could inform evaluations of the risk of prenatal transfusion transmission of the Zika virus.