FETAL IMMUNOLOGICAL AND HEMATOLOGICAL-CHANGES IN INTRAUTERINE INFECTION

Objective To study fetal immunological and haematological changes to i ntrauterine infection. Design In 37 pregnancies at risk of intrauterin e infection, fetal blood obtained by cordocentesis at 20 to 36 weeks g estation was used for differential leucocyte counts, platelet count, e numeration of lymphocyte subpopulations, and neutrophil adhesion recep tor expression. Setting Harris Birthright Research Centre for Fetal Me dicine, London. Results All four fetuses with viral infections had pla telet counts below the 5th centile and three had natural killer (NK) c ell counts greater than the 95th centile of the normal range. Similarl y, all five fetuses with bacterial or candidal infection had neutrophi l 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 thr ombocytopenia in response to viraemia, and neutrophilia in response to bacteraemia from at least 21 weeks gestation.