Objective: Our purpose was to determine whether plasma concentrations of placenta growth factor may be used as a marker for women who ultimately have severe preeclampsia.
Study design: We performed a nested case-control study to compare plasma concentrations of placenta growth factor in women with severe preeclampsia with the concentrations in normotensive pregnant control subjects. Plasma samples were collected at <20 weeks' gestation and again in the third trimester. Twenty-two women who ultimately had severe preeclampsia were matched for gestational age at delivery with 22 normotensive control subjects. Placenta growth factor concentrations were measured by a specific antigen capture enzyme-linked immunosorbent assay. Comparisons were made by using the Mann-Whitney U test for nonparametric data such as placenta growth factor concentrations. The Student t test was used for parametric data.
Results: A total of 880 pregnant women were screened. Severe preeclampsia developed in 22, for an incidence of 2.5%. As expected, women with severe preeclampsia had significantly higher systolic and diastolic blood pressures, and their infants had lower birth weights. Placental weights at delivery were similar between those with severe preeclampsia and control subjects (659 vs 699 g; P =.51). During the third trimester, the median placenta growth factor concentrations were significantly lower in women with severe preeclampsia than in normotensive control subjects (125 vs 449 pg/mL; P =.003). When samples drawn at <20 weeks' gestation were compared, there was no difference between the group with severe preeclampsia and those who remained normotensive (98.8 vs 56.34 pg/mL; P =.15).
Conclusion: During the third trimester, patients with severe preeclampsia have decreased maternal concentrations of placenta growth factor. This difference is not seen earlier in pregnancy. Lower concentrations of placenta growth factor may be a result of severe preeclampsia rather than a causal factor. Placenta growth factor is not a good marker for the subsequent development of severe preeclampsia.