Plasma Volume and Glomerular Filtration Rate in Pregnancy and Their Relation to Differences in Fetal Growth

Summary Plasma volume and glomerular filtration rate were measured serially during pregnancy and again three months after delivery in nine healthy multigravidae with normal past obstetric histories, and in eleven multigravidae who had a history of reproductive failure (“poor reproducers”). The increase of plasma volume was less in the “poor reproducers” than in the normal women, largely but not entirely associated with babies of lower birthweight. As a reflection of the association there was a marked negative correlation between the birthweight of the baby and the lowest haemoglobin concentration reached by the mother. The rise in glomerular filtration rate was also less in the “poor reproducers” than in the normal women and in pregnancies where the baby was small the rate tended to fall from its peak value during the second half of pregnancy.