Study funding
This study was supported by grants from the Fetal Medicine Foundation (UK Charity No: 1037116). Reagents and equipment for the measurement of serum placental growth factor were provided free of charge by Roche Diagnostics, and PerkinElmer Life and Analytical Sciences. These bodies had no involvement in the study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the article for publication.