The effect of parity on plasma total protein, albumin, urea and -amino nitrogen levels during pregnancy.

Abstract

SummaryThe plasma levels of total protein, albumin, urea and α‐amino nitrogen have been compared in primigravidae and multigravidae. At 10 weeks the plasma total protein concentration is significantly higher in multigravidae than in primigravidae and the plasma urea levels show a similar pattern, but the difference is not statistically significant; the plasma albumin and α‐amino nitrogen levels at 10 weeks are the same for each parity group. Between 10 and 28 weeks there is a decrease in the plasma levels of total protein, albumin and urea; this fall is greater for multigravidae than for primigravidae, but the difference is less marked with albumin. Plasma α‐amino nitrogen concentrations, however, appear to increase between 10 and 28 weeks, especially in primigravidae. Multigravidae show a decrease in plasma total protein, albumin and α‐amino nitrogen levels between 28 and 37 weeks, but primigravidae show a significant fall only in plasma albumin concentrations; plasma urea levels do not change significantly during this period. After delivery the plasma concentrations of urea and α‐amino nitrogen increase significantly and the levels of total protein and albumin decrease, but the changes are not statistically significant. The puerperal plasma total protein concentrations are lower in multigravidae than in primigravidae, who exhibit a bimodal frequency distribution; once again urea levels reflect the same tendency. In discussing the physiological implications of these results it is suggested that they are consistent with the hypothesis that plasma volume expansion is an important causative factor.