HOT SPRINGS, VA. — Placental growth factor, an angiogenic factor normally elevated in early pregnancy, may be a valuable biomarker for detecting pregnancies destined to become preeclamptic, Dr. Ramsey Unal said at the annual meeting of the South Atlantic Association of Obstetricians and Gynecologists.
Vascular growth factors are essential in creating and maintaining the placenta, said Dr. Unal, a resident at the Medical University of South Carolina, Charleston. Both placental growth factor (PIGF) and vascular endothelial growth factor (VEGF) are higher in early pregnancy and decrease as delivery approaches. Another factor, soluble FMS-like tyrosine kinase 1 (sFlt1), increases later in pregnancy and binds both PIGF and VEGF, decreasing their bioavailability as the pregnancy nears term.
“Normal pregnancy is a balancing act in angiogenesis,” Dr. Unal said. “At the beginning, during placentation, you have a proangiogenic state and toward the end, in preparation for delivery; you shift to an antiangiogenic state. In preeclampsia, we think the shift happens too early and is too exaggerated.”
Dr. Unal investigated the utility of using second-trimester PIGF and sFLT1 levels as predictors of preeclampsia. If the levels were already abnormal in the second trimester, she reasoned, they could easily be included in the quad screen to flag women at risk for preeclampsia.
Her retrospective study included 64 women: 21 of them developed preeclampsia and were delivered for that reason, 34 were healthy women with uncomplicated term deliveries, and 9 had chronic, prepregnancy hypertension. All the women had singleton pregnancies. Dr. Unal performed enzyme-linked immunosorbent assay testing for PIGF and sFLT1 on stored quad screen serum samples obtained from these women at 16–24 weeks' gestation.
PIGF was significantly lower in the group that went on to develop preeclampsia than it was in the normal control group, she said (mean 85.3 pg/mL vs. 133 pg/mL). There were no significant differences in sFLT1 levels between the groups. However, women with chronic hypertension had slightly, though not significantly, lower sFLT1 levels than did normal controls—an interesting relationship, Dr. Unal said. “Preeclampsia is a disease of the placenta, and hypertension can also cause placenta problems.”
PIGF levels could easily be drawn from quad screen sera, adding yet another valuable biomarker to the routine screen. “But we need a large, prospective trial before any recommendations can be made,” she said.