Maternal Health

Preeclampsia Warning Signs in the Third Trimester

Content reviewed against published ACOG, NIH, Preeclampsia Foundation guidelines

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Your health matters just as much as your baby's. If you are dealing with preeclampsia warning signs in the third trimester, here is what you need to know.

The short answer

Preeclampsia is a serious pregnancy complication characterized by high blood pressure and signs of organ damage, typically occurring after 20 weeks of pregnancy. It affects 5-8% of pregnancies and can progress rapidly. Warning signs include persistent severe headache, vision changes (blurring, spots, light sensitivity), sudden severe swelling (especially face and hands), upper abdominal pain (especially right side), nausea or vomiting in the second half of pregnancy, and sudden weight gain from fluid retention. These symptoms require immediate medical evaluation.

Key takeaways

  • Preeclampsia is a serious pregnancy complication characterized by high blood pressure and signs of organ damage, typically occurring after 20 weeks of pregnancy. It affects 5-8% of pregnancies and can progress rapidly. Warning signs include persistent severe headache, vision changes (blurring, spots, light sensitivity), sudden severe swelling (especially face and hands), upper abdominal pain (especially right side), nausea or vomiting in the second half of pregnancy, and sudden weight gain from fluid retention. These symptoms require immediate medical evaluation.
  • Usually normal when: Mild swelling of feet and ankles at the end of the day, which is common in pregnancy
  • Call your doctor if: You have a severe headache with vision changes (blurring, spots, flashing lights)
  • Varies by age — see the age-by-age breakdown below
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By Age

What to expect by age

20-28 weeks

Early-onset preeclampsia (before 34 weeks) is less common but tends to be more severe. Risk factors include first pregnancy, previous preeclampsia, chronic hypertension, kidney disease, diabetes, autoimmune conditions, obesity, age over 35 or under 20, IVF pregnancy, and carrying multiples. If you have risk factors, your provider may recommend low-dose aspirin starting at 12-16 weeks. Regular prenatal visits include blood pressure checks and urine screening, which help catch early signs. If diagnosed this early, close monitoring and possible hospitalization may be needed.

28-37 weeks

This is the most common window for preeclampsia to develop. Learn and watch for warning signs between appointments: persistent headache not relieved by acetaminophen, visual disturbances (flashing lights, blurry vision, spots), pain in the upper right abdomen or shoulder, sudden significant swelling of face, hands, or feet, and nausea or vomiting. If your blood pressure at a prenatal visit is elevated (140/90 or higher), additional testing including blood work and urine protein will be ordered. Treatment depends on severity and gestational age, and may include blood pressure medication, magnesium sulfate, and close monitoring.

37+ weeks and postpartum

Late-onset preeclampsia and postpartum preeclampsia (occurring up to 6 weeks after delivery) are important to recognize. The cure for preeclampsia is delivery, and at 37+ weeks, induction is typically recommended. After delivery, continue to watch for preeclampsia symptoms for several weeks. If you develop severe headache, vision changes, difficulty breathing, or upper abdominal pain after going home from the hospital, seek emergency care. Postpartum preeclampsia can develop even in people who had normal blood pressure throughout pregnancy.

What Should You Do?

When to take action

Probably normal when...
  • Mild swelling of feet and ankles at the end of the day, which is common in pregnancy
  • Occasional mild headaches that respond to rest and hydration
  • Blood pressure readings that remain normal at prenatal visits
Mention at your next visit when...
  • You notice a significant increase in swelling, particularly in your face and hands
  • You have a persistent headache that does not respond to acetaminophen, rest, or hydration
  • You are gaining weight rapidly (more than 2 pounds in a week) from fluid retention
  • You have any risk factors for preeclampsia and want to discuss prevention
Act now when...
  • You have a severe headache with vision changes (blurring, spots, flashing lights)
  • You have upper right abdominal pain or right shoulder pain, especially with nausea or vomiting
  • You have a blood pressure reading of 160/110 or higher at home
  • You have sudden severe swelling with difficulty breathing or chest tightness
  • You experience decreased fetal movement along with any preeclampsia symptoms

Doctor Visit Checklist

Bring this checklist to your next pediatrician visit to discuss Preeclampsia Warning Signs in the Third Trimester.

Things to mention

  • You notice a significant increase in swelling, particularly in your face and hands
  • You have a persistent headache that does not respond to acetaminophen, rest, or hydration
  • You are gaining weight rapidly (more than 2 pounds in a week) from fluid retention
  • You have any risk factors for preeclampsia and want to discuss prevention

Observations to share

  • You notice a significant increase in swelling, particularly in your face and hands
  • You have a persistent headache that does not respond to acetaminophen, rest, or hydration
  • You are gaining weight rapidly (more than 2 pounds in a week) from fluid retention

Urgent signs to report immediately

  • You have a severe headache with vision changes (blurring, spots, flashing lights)
  • You have upper right abdominal pain or right shoulder pain, especially with nausea or vomiting
  • You have a blood pressure reading of 160/110 or higher at home

My notes

From ismybabyalright.com — free, evidence-based baby health guides

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True labor is characterized by regular contractions that increase in frequency, duration, and intensity over time, and do not stop with rest, hydration, or position changes. Other signs that labor may be approaching include loss of the mucus plug (bloody show), water breaking (rupture of membranes), persistent lower back pain, and a feeling of increased pelvic pressure. First-time parents are generally advised to head to the hospital when contractions are about 5 minutes apart, lasting 1 minute each, for at least 1 hour (the 5-1-1 rule).

Late Postpartum Preeclampsia

Postpartum preeclampsia can develop within 48 hours of delivery or up to 6 weeks after birth, even in people who did not have preeclampsia during pregnancy. It is characterized by high blood pressure and possible organ damage. It is a medical emergency that requires immediate treatment. Knowing the warning signs after delivery is critical.

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Frequently asked questions

Is preeclampsia warning signs in the third trimester normal?
Preeclampsia is a serious pregnancy complication characterized by high blood pressure and signs of organ damage, typically occurring after 20 weeks of pregnancy. It affects 5-8% of pregnancies and can progress rapidly. Warning signs include persistent severe headache, vision changes (blurring, spots, light sensitivity), sudden severe swelling (especially face and hands), upper abdominal pain (especially right side), nausea or vomiting in the second half of pregnancy, and sudden weight gain from fluid retention. These symptoms require immediate medical evaluation.
When should I call the doctor about preeclampsia warning signs in the third trimester?
You have a severe headache with vision changes (blurring, spots, flashing lights) You have upper right abdominal pain or right shoulder pain, especially with nausea or vomiting You have a blood pressure reading of 160/110 or higher at home
When is preeclampsia warning signs in the third trimester normal?
Mild swelling of feet and ankles at the end of the day, which is common in pregnancy Occasional mild headaches that respond to rest and hydration Blood pressure readings that remain normal at prenatal visits
What causes preeclampsia warning signs in the third trimester?
Preeclampsia is a serious pregnancy complication characterized by high blood pressure and signs of organ damage, typically occurring after 20 weeks of pregnancy. It affects 5-8% of pregnancies and can progress rapidly. Warning signs include persistent severe headache, vision changes (blurring, spots, light sensitivity), sudden severe swelling (especially face and hands), upper abdominal pain (especially right side), nausea or vomiting in the second half of pregnancy, and sudden weight gain from fluid retention. These symptoms require immediate medical evaluation. Common explanations include: Mild swelling of feet and ankles at the end of the day, which is common in pregnancy. Occasional mild headaches that respond to rest and hydration.
What should I mention to my pediatrician about preeclampsia warning signs in the third trimester?
You should mention preeclampsia warning signs in the third trimester at your next visit if: You notice a significant increase in swelling, particularly in your face and hands. You have a persistent headache that does not respond to acetaminophen, rest, or hydration. You are gaining weight rapidly (more than 2 pounds in a week) from fluid retention.
Is preeclampsia warning signs in the third trimester normal at 20-28 weeks?
Early-onset preeclampsia (before 34 weeks) is less common but tends to be more severe. Risk factors include first pregnancy, previous preeclampsia, chronic hypertension, kidney disease, diabetes, autoimmune conditions, obesity, age over 35 or under 20, IVF pregnancy, and carrying multiples. If you have risk factors, your provider may recommend low-dose aspirin starting at 12-16 weeks. Regular prenatal visits include blood pressure checks and urine screening, which help catch early signs. If diagnosed this early, close monitoring and possible hospitalization may be needed.
Is preeclampsia warning signs in the third trimester normal at 28-37 weeks?
This is the most common window for preeclampsia to develop. Learn and watch for warning signs between appointments: persistent headache not relieved by acetaminophen, visual disturbances (flashing lights, blurry vision, spots), pain in the upper right abdomen or shoulder, sudden significant swelling of face, hands, or feet, and nausea or vomiting. If your blood pressure at a prenatal visit is elevated (140/90 or higher), additional testing including blood work and urine protein will be ordered. Treatment depends on severity and gestational age, and may include blood pressure medication, magnesium sulfate, and close monitoring.
Should I go to the ER for preeclampsia warning signs in the third trimester?
Seek emergency care if you have a severe headache with vision changes (blurring, spots, flashing lights), or if you have upper right abdominal pain or right shoulder pain, especially with nausea or vomiting. When in doubt, call your pediatrician's after-hours line for guidance.
Does preeclampsia warning signs in the third trimester go away on its own?
In many cases, preeclampsia warning signs in the third trimester resolves on its own, especially when mild swelling of feet and ankles at the end of the day, which is common in pregnancy. By 37+ weeks and postpartum, late-onset preeclampsia and postpartum preeclampsia (occurring up to 6 weeks after delivery) are important to recognize. The cure for preeclampsia is delivery, and at 37+ weeks, induction is typically recommended. After delivery, continue to watch for preeclampsia symptoms for several weeks. If you develop severe headache, vision changes, difficulty breathing, or upper abdominal pain after going home from the hospital, seek emergency care. Postpartum preeclampsia can develop even in people who had normal blood pressure throughout pregnancy.
ACOGNIHPREECLAMPSIA FOUNDATION

References

  1. [1]American College of Obstetricians and Gynecologists. Preeclampsia and High Blood Pressure During Pregnancy. ACOG FAQ, 2022. ACOG
  2. [2]National Institute of Child Health and Human Development. Preeclampsia and Eclampsia. NICHD, 2024. NIH
  3. [3]Preeclampsia Foundation. Signs and Symptoms. Preeclampsia.org, 2024. Preeclampsia Foundation

All content follows our editorial policy and is reviewed against published clinical guidelines.

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Bottom line

Most cases of preeclampsia warning signs in the third trimester are normal. Talk to your pediatrician if you have a severe headache with vision changes (blurring, spots, flashing lights).

Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.

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Late Postpartum Preeclampsia

Postpartum preeclampsia can develop within 48 hours of delivery or up to 6 weeks after birth, even in people who did not have preeclampsia during pregnancy. It is characterized by high blood pressure and possible organ damage. It is a medical emergency that requires immediate treatment. Knowing the warning signs after delivery is critical.

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