Risk factors for pre-eclampsia

Patient-related factors: Multiparous patients with a past history of severe preeclampsia are a high risk population which should be identified early i n pregnancy. Selection on this criterion alone is however insufficient for large scale screening and prevention because most of the susceptible women are nulliparous. Search for a particular familial or personal history of va scular disorders can be helpful. The usefulness of blood pressure measureme nts during the second trimester has not been proven. Markers: There is a significant association between pre-eclampsia and a lar ge number of biological markers. No one assay can however fulfill the requi rements for effective early screening because sensitivity is too low or the rate of false positives is too high, or because the examination is too inv asive or costly. Doppler anomalies: Doppler exploration of the uterine arteries at 20 to 24 weeks gestation offers satisfactory sensitivity and specificity but the pos itive predictive value is low. Persistence of a bilateral notch beyond 24 w eeks considerably limits the number of false positives. More than half of t he patients with this anomaly will develop hypertension during pregnancy. W hile no one marker fulfills ail the prerequisites for effective screening, a combination of several tests may be useful. hCG assay during the second t rimester in association with Doppler exploration of the uterine arteries ap pears to be a promising combination. Prevention: Starting with these markers or risk factors, the goal is to dev elop a prevention scheme using low-dose aspirin, the only evidence-based pr eventive treatment to date. Further trials are required to test simultaneou sly the predictive value and impact (versus placebo) of proposed strategies .