Placental Growth Factor (PlGF) testing

This leaflet is for women and birthing people between 20+0 and 36+6 weeks of pregnancy who have developed new symptoms: high blood pressure (hypertension) and/or protein in your wee (proteinurea). These two symptoms suggest you may be developing pre-eclampsia, but some other tests are recommended to confirm this.

When and why do you offer PlGF testing?

Pre-eclampsia is a potentially serious pregnancy complication that affects some women and birthing people, usually in the second half of pregnancy, or soon after the baby is born.

If you have symptoms that suggest pre-eclampsia, we recommend a blood test that checks the level of placental growth factor (PlGF). PlGF is a protein produced by the placenta which promotes the growth of new blood vessels. If the level of PlGF is low, it indicates that the placenta is not functioning as it should.

The PlGF test is a simple blood test usually taken from your arm. It is only recommended to be tested for when you are between 20 and 37 weeks pregnant. At the moment, research suggests that there is only any benefit to you being tested once during pregnancy.

What do the results mean?

We recommend staying at the hospital to wait for the PlGF result (this should take 1-2 hours). The result will be used alongside other assessments when we recommend a plan of care. A positive test result suggests an increased risk of preterm birth due to pre-eclampsia. This can be because you go into labour by yourself, or because we recommend early birth.

A negative result is 100 or higher. 98% of women or birthing people with this result will not give birth due to pre-eclampsia within 14 days of the test. If you are less than 35 weeks pregnant on average you are likely to have your baby with 62 days. If you are 35-37 weeks pregnant on average you are likely to have your baby within 16 days.

Even if you have a negative test, or you don’t have pre-eclampsia, you may still have pregnancy hypertension and will be offered additional monitoring in pregnancy.

A positive result of between 12 and 99 suggests your placenta is not working as well as it should. Depending on the rest of your assessments you will be recommended to have blood pressure monitoring and your wee tested for protein in clinic 22 twice a week. A result of less than 100 correctly identifies 95-96% of women and birthing people with pre-eclampsia who will give birth within 14 days. If you are less than 35 weeks pregnant on average you are likely to have your baby with 23 days. If you are 35-37 weeks pregnant on average you are likely to have your baby within 9 days.

A positive result of less than 12 suggests your placenta is severely compromised. It will be recommended that you are admitted to the antenatal ward for closer monitoring of you and your baby. If you are less than 35 weeks with this result, it is very likely that you will have your baby early (94% of women and birthing people with this result). If you are less than 35 weeks pregnant on average you are likely to have your baby with 9 days. If you are 35-37 weeks pregnant on average you are likely to have your baby within 4 days.

Benefits

The PlGF result reduces the amount of time to diagnose pre-eclampsia. This allows us to make an appropriate plan of care, whether it is additional hospital visits, or admission to the antenatal ward.

Risks

There may be some mild discomfort when taking the blood test.

Alternatives

If you do not wish to have the PlGF level checked we will continue to monitor your blood pressure and urine.

Further information

Action on pre-eclampsia (opens in a new tab)

Sources of evidence

National Institute for Health and Care Excellence (NICE) (2022) PlGF-based testing to help diagnose suspected preterm pre-eclampsia.