Plasma viscosity during normal pregnancy

The changes in plasma viscosity and plasma proteins were serially measured in 14 nulli- and 10 multiparae, during their normal pregnancies. As compared to the non-pregnant value plasma viscosity decreased in the first trimester, but increased during the second and third trimester until term. At 37 weeks, the plasma viscosity value exceeded the non-pregnant value, the difference being statistically significant. The increase in plasma viscosity during the second and third trimester of pregnancy was determined by the rise in fibrinogen concentration, which overruled the plasma viscosity lowering influence of the falling total serum protein concentratio