Chronic histiocytic intervillositis (CHI) is associated with severe and recurrent obstetrical complications. A link between anti-HLA Antibodies (Ab) and CHI has recently been established. At the Etablissement Français du Sang (EFS), donors who have already given birth once and have high levels of anti-HLA are excluded from donating apheresis platelets and therapeutic plasma to prevent TRALI (Transfusion Related Acute Lung Injury). No studies have examined the obstetrical history of these donors. The question is: is there an association between anti-HLA levels and obstetrical complications?

Chronic histiocytic intervillositis (CHI) is a rare condition with an incidence of around 5 in 10,000 pregnancies. It is defined by major infiltration of the intervillous cavity by CD68+ maternal histiocytes, associated with fibrin deposition on the villous surface.

CHI is associated with severe obstetrical complications and a very high recurrence rate, estimated at between 70% and 100%. These complications include early and late miscarriage, fetal death, severe growth retardation in surviving fetuses, and premature delivery. The survival rate reported in the literature varies between 30% and 50%.

Anti-HLA antibodies are present in 54% of pregnant women at the end of pregnancy, and their rate increases towards the end of pregnancy. The presence of HLA antibodies also increases with the number of pregnancies, and is found in up to 74% of cases after more than 2 deliveries.

The research question concerns the existence of a statistically significant association between the presence of high levels of anti-HLA antibodies and the occurrence of one or more obstetric complications.

Inclusion Criteria:

• Female blood donors who have been tested for anti-HLA antibodies in the context of TRALI prevention between 2010 and 2020 at EFS Nouvelle Aquitaine [The donors meet the conditions of the Order of December 17, 2019 establishing the selection criteria for blood donors and are over 18 years old, are not protected persons and understand French well]
• Women who have already given birth at least once (non-nulliparous women)
• Women who have not expressed their opposition at the time of donation to participating in a research project and to be contacted

Exclusion Criteria:

• None [Donors meet the conditions of the Order of December 17, 2019 establishing the selection criteria for blood donors and are over 18 years old, are not protected persons and understand French well]

Blood donors who were screened for anti-HLA Ab between 2010 and 2020 as part of TRALI prevention at the EFS Poitiers site histocompatibility laboratory.