Many risk factors for hypertension in pregnancy arise from obstetric factors such as multiple gestation, prior obstetric history and molar pregnancy.  The role of epidemiologically discovered risk factors such as body mass index, family history, parity, inter-pregnancy interval and partner status are not perfect as markers of risk within any individual pregnancy and great accuracy in prediction is now afforded by placental function tests specific to placental blood flow, endocrine and immune activity.

Assessment of placental function is both a new and an old idea and current research has identified the cellular biology of the placenta in more detail.  The immunological and cytokine functions of the placenta clearly contribute to maternal adaptation to pregnancy, including blood pressure regulation. The role of recently defined anti-angiogenic factors and hypoxia regulated molecules (soluble FLT-1 (sFLT-1) and placental growth actor (PlGF)) looks to be a major development in our capacity to define placental function in early pregnancy, or at least, preceding the onset of clinical symptoms and signs. The interaction of these molecular systems with placental cell processes such as apoptosis, and villous formation and invasion of the endometrium, may explain early placental failure in preeclampsia. The likely value of a predictive test is most challenging in the women in their first pregnancy who constitute the greatest burden of disease.

A composite “scoring” of maternal factors, placental function tests, maternal immunological adaptability and possibly utero-placenta blood flow tests will be more likely to predict an individual case of preeclampsia than any test alone.  However, the promise of reliable blood and urine testing of stable molecules reflecting the various clinical aspects of “toxaemia” is fast being realized. Data regarding significant outcomes including post-partum haemorrhage, seizures, fetal growth restriction and other markers of severity of preeclampsia also appear to track with changes in sFLT-1 and PLGF but need to be confirmed in large scale studies.