Pregnancy and the erythrocyte sedimentation rate

Objectives To determine the range of erythrocyte sedimentation rate values obtained in healthy pregnant women. To examine the effect of gestational age and haemoglobin concentration on erythrocyte sedimentation rate.

Setting Queen Charlotte's Hospital, London, UK.

Design Cross sectional descriptive study.

Population Healthy pregnant women attending for routine outpatient antenatal visits at Queen Charlotte's Hospital in London.

Methods Erythrocyte sedimentation rate was determined by the Westergren method, haemoglobin concentration by automated cell counter and gestational age by ultrasonography. The median and 95% reference range was determined for erythrocyte sedimentation rate values obtained. Linear regression analysis was used to determine the influence of haemoglobin concentration and gestational age on erythrocyte sedimentation rate.

Results For 1019 women examined, the range of erythrocyte sedimentation rate values obtained was 4–112 mm/h. Gestational age and haemoglobin concentration both significantly influenced erythrocyte sedimentation rate. (P<0.0001). For non-anaemic women the 95% reference range rose from 18–48 mm/h in the first half of pregnancy to 30–70 mm/h in the second half of pregnancy. For anaemic women the corresponding reference ranges were 21–62 mm/h and 40–95 mm/h, respectively.

Conclusion For the correct interpretation of erythrocyte sedimentation rate values obtained during pregnancy gestational age and haemoglobin concentration must be taken into account.