Negative predictive values were moderate at 73.3% (95% CI, 64.3%-81.1%) and 72.0% (95% CI, 63.0%-79.9%), respectively, indicating that low ratios had a limited ability to rule out stillbirth.<h4>Conclusions and relevance</h4>This case-control study found that a high sFlt-1:PlGF ratio using clinically relevant thresholds was associated with stillbirth and corresponded to an estimated 13-fold increased risk. This evidence concerns the gene PGF and Stillbirth.