Retrospective analysis of platelet numbers and volumes in normal pregnancy and in pre‐eclampsia

OBJECTIVE: To determine the distribution of platelet volumes and numbers through pregnancy, and to compare these to changes in platelet volumes and numbers in women with pre-eclampsia. SUBJECTS: Four hundred twenty-eight women with normal pregnancy from whom four or more platelet measurements were available were identified. 74 women with pre-eclampsia (blood pressure > or = 140/90 mmHg, at least 0.5 g protein/24 h urine collection) from whom platelet measurements were available between 27 and 30 weeks of gestation were identified. RESULTS: Mean platelet volume and platelet number remained constant in normal pregnancies between the first trimester and the end of pregnancy. A persistent increase of > or = 0.8 fl (> or = 90th centile) in mean platelet volume was found in 14 out of 15 pre-eclamptic patients between 24 weeks and 38 weeks of gestation and in only 13 of 428 normal pregnant individuals. Platelet numbers were decreased by > or = 50 x 10(9)/l (i.e. to less than the 10th centile) in 12 of the 15 patients with pre-eclampsia. 10% of the normal pregnant population showed a similar decline in platelet numbers showing that changes in platelet numbers may be a less accurate assessment of the development of pre-eclampsia. CONCLUSION: We suggest that longitudinal determination of platelet volumes may be of use in identifying those women at risk of pre-eclampsia.