Fetal immunological and haematological changes in intrauterine infection

Abstract

OBJECTIVE: To study fetal immunological and haematological changes to intrauterine infection. DESIGN: In 37 pregnancies at risk of intrauterine infection, fetal blood obtained by cordocentesis at 20 to 36 weeks gestation was used for differential leucocyte counts, platelet count, enumeration of lymphocyte subpopulations, and neutrophil adhesion receptor expression. SETTING: Harris Birthright Research Centre for Fetal Medicine, London. RESULTS: All four fetuses with viral infections had platelet counts below the 5th centile and three had natural killer (NK) cell counts greater than the 95th centile of the normal range. Similarly, all five fetuses with bacterial or candidal infection had neutrophil counts greater than the 95th centile of the normal range; lymphocyte subpopulations were normal. CONCLUSIONS: In pregnancies complicated by intrauterine infection, fetuses exhibit NK cell lymphocytosis and thrombocytopenia in response to viraemia, and neutrophilia in response to bacteraemia from at least 21 weeks gestation.