Regression analysis revealed a significant regression on Day 40 between fetal weight and hematocrit percentage, and fetal weight and hemoglobin, which differed between intact uterine environments (WC INT and MS) and UHO. Examination of the data suggests that intrauterine crowding results in some fetuses with lower than average body weight and hematocrit percentage and/or blood hemoglobin. It is possible that fetuses in a normal intrauterine environment are not stressed as much (e.g., insufficient nutrients) as those in a crowded environment and therefore do not show this relationship. This observation supports the hypothesis that a crowded uterine environment may indeed affect growth and hematological parameters, which could ultimately result in fetal loss. It was hoped that all “crowded” fetuses might display some anomalies due to crowding. However, it is likely that only those fetuses that will eventually be lost show any differences from fetuses in an intact uterine environment.
EPO in the Swine Fetus
EPO, in conjunction with its receptor, is a growth factor for erythroid cells, particularly the late burst-forming units and colony-forming units that precede the erythroblast series, and thus tightly controls the number of circulating RBC. To detect EPO in porcine plasma, we used a heterologous RIA procedure with a polyclonal antibody generated against human EPO. Porcine EPO is not currently available, and thus levels of EPO in porcine plasma reported are indicative of relative levels and most likely underestimate absolute levels.