Glomerular Filtration During and After Pregnancy

Summary Glomerular filtration rate was estimated by three methods in ten healthy women during pregnancy at 15 to 18 weeks, 25 to 28 weeks and 35 to 38 weeks; and again 8 to 12 weeks post‐partum. During infusion the glomerular filtration rate was found to be raised from a non‐pregnant level of about 110 ml. per minute to a plateau of about 170 ml. per minute throughout pregnancy, whether the clearance was of infused inulin or endogenous creatinine. A 24‐hour creatinine clearance, measured the day before the infusion, gave a systematically lower estimate; it rose from a non‐pregnant mean of about 100 ml. per minute to a plateau at about 150 ml. per minute, which fell in late pregnancy to about 130 ml. per minute. It is concluded that an estimate of glomerular filtration rate is only valid for the conditions under which it is measured, that infusion probably raises the rate; and that the fall in late pregnancy which has been generally regarded as an “artefact” of posture may nevertheless represent the real life situation.