06/29/2026
If you have high blood pressure in pregnancy, there is a lab test your OB can order that could help you know if your symptoms are preeclampsia or not.
It's called the sFlt‑1/PlGF ratio.
This blood test helps answer a key question...
..are these symptoms likely to be preeclampsia in the next few weeks, or do we have more time/Is this something else?
This test comes from a research study called the PROGNOSIS trial.
Here is what the research found:
A ratio < 38 is very good at ruling out preeclampsia in the next week (and likely for several weeks).
A ratio > 38 means a higher chance of developing preeclampsia in the next few weeks.
So this is mostly a “rule‑out” tool.
It's especially powerful for saying preeclampsia is unlikely right now. Which means we can make safer, calmer decisions about admission, monitoring, and delivery timing. It also helps us know if we have time to rule out other causes of your symptoms, such as preeclampsia mimickers. Or is this true preeclampsia?
This test assesses the balance between sFlt‑1 (anti‑angiogenic, placenta‑stress signal) and PlGF (pro‑angiogenic, “healthy vessel” signal).
When the anti-angiogenic side dominates, it suggests placental dysfunction, often before symptoms fully show up.
Right now, this testing is usually available only through obstetric clinicians (OBs, MFMs, some hospital-based midwives).