Fetal gender and several cytokines are associated with the number of fetal cells in maternal blood--an observational study.

Objective To identify factors influencing the number of fetal cells in maternal blood. Methods A total of 57 pregnant women at a gestational age of weeks 11–14 were included. The number of fetal cells in maternal blood was assessed in 30 ml of blood using specific markers for both enrichment and subsequent identification. Results Participants carrying male fetuses had a higher median number of fetal cells in maternal blood than those carrying female fetuses (5 vs. 3, p = 0.04). Certain cytokines (RANTES, IL-2 and IL-5) were significantly associated with the number of fetal cells in maternal blood. Conclusion The number of fetal cells in maternal blood is associated with certain cytokines and fetal gender.