Who is (not) at risk? Prognostic tests and models in obstetrics with a focus on pre-eclampsia and preterm birth

Effective and efficient care relies on accurate and individualized estimates of risk that a certain health outcome (favourable or unfavourable) occurs. Thereby only those patients who are at high risk for an outcome can be selected to undergo a procedure or to receive (preventive) treatment or intervention. Prognostic factors, or more than one factor combined in a multivariable model, can be used to estimate such risks.
This thesis (1) gives an overview of available prediction models in obstetrics and how well they could or should be used in the context of current evidence; (2) evaluates the potential of risk changes over time to predict complications of pre-eclampsia with the use of an existing model; (3) synthesizes available evidence for commonly investigated biomarkers for pre-eclampsia and those that warrant further investigation for potential use as a biomarker; (4) investigates the ability of combinations of patient characteristics and ultrasound to differentiate between women at low and high risk for pre-eclampsia or recurrent preterm birth; and (5) assesses a previously reported association between CRL and preterm birth to evaluate its potential role in predicting spontaneous preterm birth.
It is our impression that so far, efforts to predict outcomes in obstetrics have not moved far beyond the development phase. We did not find evidence that any test or prediction model described here would improve clinical outcomes. At this stage we cannot advise a new model or test that should be used in clinical practice. We encourage researchers to perform external validation and impact studies.