The Natural History of Fetomaternal Alloimmunization to the Platelet-Specific Antigen HPA-1a (PlA1, Zwa) as Determined by Antenatal Screening

摘要: Immunization against the human platelet antigen (HPA)-1 alloantigen is most common cause of severe fetal and neonatal thrombocytopenia. Fetal therapy has substantial risks its indications need better definition. Of 24,417 consecutive pregnant women, 618 (2.5%) were HPA-1a negative whom 385 entered an observational study. All HLA-DRB3*0101 genotyped screened for anti–HPA-1a. Their partners neonates HPA-1 latter assessed by cord blood counts cerebral ultrasound scans. Anti–HPA-1a was detected in 46 387 pregnancies (12.0%; 95% CI 8.7%-15.2%). but one positive (odds ratio 140; 19-1035; P < .00001). One baby died utero, 26 HPA-1a–positive babies born to women with persistent antenatal antibodies, 9 severely thrombocytopenic (8 a count <10 × 109/L, 1 large porencephalic cyst), 10 mildly thrombocytopenic, whereas 7 had normal counts. Severe thrombocytopenia significantly associated third trimester anti–HPA-1a titer ≥ 1:32 ( = .004), not observed either transient or postnatal-only antibodies. alloimmunization complicates 350 unselected pregnancies, resulting 1:1,200. typing combined titration allows selection majority at risk