Introduction:
Collecting cord blood (CB) for banking is a common practice in obstetrics. There are many studies in the literature assessing the use of the obtained stem cells in medicine, however, there are few examining the interference of the collection procedure with the delivery mechanism and maternal blood loss.

Aim of the research:
To assess the effect of this procedure on perioperative maternal blood loss during caesarean section (CS).

Material and methods:
It was a retrospective, observational study. It included 238 women in whom a CS was performed and umbilical cord blood (CB) was collected using the in utero method. The control group consisted of 1106 patients who underwent CS without CB collection.

Results:
We observed statistically significant lower values of hemoglobin (Hb) (11.5 g/dl vs. 11.7 g/dl, p = 0.04) and hematocrit (Hct) (33.7% vs. 34.4%, p = 0.03) in the study group compared with controls after the surgery. In the study group, we also observed a greater median decrease in the concentration of Hb (1.1 g/dl vs. 0.8 g/dl, p < 0.001) and Hct (3.05% vs. 2.2%, p < 0.001). Platelet levels did not change. We recorded no difference in the incidence rates of postpartum anemia (Hb < 10 g/dl) and severe postpartum anemia (Hb < 7 g/dl).

Conclusions:
In utero CB collection during CS is associated with a statistically significant increase in perioperative blood loss. The difference is small and of no clinical significance in the healthy population of young patients undergoing CS.