Identification of feto-maternal haemorrhage around labour using flow cytometry immunophenotyping

Abstract Objective To determine the normal range of feto-maternal haemorrhage (FMH) due to labour, and to investigate if the type of delivery might influence the volume of FMH. Study design In a prospective cohort trial setting we studied 346 women in their 3rd trimester of gestation. Women were classified according to the type of delivery: vaginal, instrumental and caesarean section. Fetal erythrocytes in maternal blood were measured by flow cytometry immunophenotyping using a fluorochrome-conjugated monoclonal antibody against fetal haemoglobin. For each woman, two blood samples were studied; one pre-labour and one post-labour. The difference between FMH values obtained post- and pre-delivery was established as FMH due to delivery. Results FMH due to labour ranged between p  = 0.001), and between instrumental deliveries and caesarean sections ( p  = 0.008). Conclusions FMH due to labour is small. The route of delivery could not be established as a risk factor for FMH but caesarean section increases the risk of suffering a higher amount of transplacental bleeding.