Preeclampsia Risk: What Changes When You've Had It Before

By Jim Edwards, MD, FACOG. Board-Certified Maternal-Fetal Medicine Physician.

May is Preeclampsia Awareness Month, the annual campaign led by the Preeclampsia Foundation to raise awareness of one of the most consequential complications of pregnancy. May 22 is World Preeclampsia Day. If you are reading this because you had preeclampsia in a previous pregnancy and you are thinking about, or already in, another pregnancy, this article is written for you.

You already know preeclampsia is not a straightforward complication. It can arrive with urgency, and it often ends a pregnancy earlier than anyone planned. Going into a subsequent pregnancy carrying that history changes how you think about the months ahead. It also changes how your care team approaches them.

This guide explains what the evidence says about preeclampsia recurrence risk, why low-dose aspirin matters, what closer monitoring looks like, and which warning signs deserve same-day attention.

How likely is preeclampsia to recur in a second pregnancy?

Preeclampsia recurrence risk depends substantially on how severe your first episode was and how early in the pregnancy it occurred.

• After a single prior episode of preeclampsia, the recurrence risk in a subsequent pregnancy is approximately 13% to 25%. That is meaningfully higher than the 2% to 8% baseline risk in the general population.
• After preeclampsia with severe features (very high blood pressures, low platelets, abnormal liver enzymes, or HELLP syndrome), recurrence rates climb further. Studies report figures of 25% to 65% depending on the population studied.
• After early-onset preeclampsia (delivery before 34 weeks), the risk of any hypertensive disorder of pregnancy in a subsequent pregnancy is particularly elevated, and earlier recurrence is more likely.

These numbers are not meant to alarm you. Many people with a history of preeclampsia have uncomplicated subsequent pregnancies. But the recurrence risk is real, and it is the reason your next pregnancy will, and should, be managed differently.

Why does preeclampsia come back?

Preeclampsia originates in abnormal placentation early in pregnancy. The trophoblast cells that should remodel the maternal spiral arteries do not invade as deeply as they should. The result is a placenta that cannot keep up with the growing demands of pregnancy, releasing factors into the maternal circulation that drive hypertension and end-organ injury.

The conditions that contributed to abnormal placentation in your first pregnancy, whether genetic, immunologic, vascular, or related to underlying medical conditions like chronic hypertension or diabetes, are likely still present going into the next. That is one reason why recurrence risk is elevated, and it is why prevention strategies focus on placental function and vascular health from early pregnancy onward.

Low-dose aspirin: the most evidence-based prevention

For people with a prior history of preeclampsia, low-dose aspirin is currently the most effective evidence-based intervention to reduce recurrence risk. The American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM) jointly recommend low-dose aspirin (81 mg daily) for any patient with one or more high-risk factors, including a prior history of preeclampsia.

The ASPRE trial, a multicenter randomized controlled trial published in the New England Journal of Medicine in 2017, demonstrated that low-dose aspirin started between 11 and 14 weeks reduced preterm preeclampsia (delivery before 37 weeks) by approximately 62% in high-risk women. Subsequent meta-analyses have reinforced these findings, particularly when aspirin is initiated before 16 weeks of gestation.

When to start. Current ACOG and SMFM Practice Advisory guidance supports initiating low-dose aspirin between 12 and 28 weeks of gestation, ideally before 16 weeks. If you are planning a pregnancy or have just confirmed one, raise aspirin timing at your earliest prenatal visit.

How long to take it. Aspirin is continued daily through delivery.

Is it safe? Low-dose aspirin has an excellent safety profile in pregnancy at the recommended 81 mg dose. It does not meaningfully increase bleeding risk, and it is not associated with adverse fetal effects.

What closer monitoring looks like in a pregnancy after preeclampsia

A pregnancy after preeclampsia typically involves more frequent prenatal visits, earlier and more targeted testing, and a lower threshold to evaluate any new symptom. Specifics vary by practice and by the severity of your prior episode, but you can generally expect:

• More frequent blood pressure checks. Blood pressure is checked at every prenatal visit. Many providers also recommend home blood pressure monitoring, especially in the third trimester. If you do not have a home cuff, ask your provider which device to use.
• Baseline and surveillance labs. A urine protein-to-creatinine ratio or 24-hour urine collection is often obtained at baseline so that a later change can be detected. Liver function tests and platelet counts are checked if blood pressure trends upward or symptoms develop.
• Growth ultrasounds. Because preeclampsia is associated with placental insufficiency that can restrict fetal growth, serial growth ultrasounds every four weeks are commonly recommended starting in the third trimester. These exams assess fetal size, amniotic fluid volume, and umbilical artery Doppler when there is poor fetal growth.
• Antenatal fetal testing. Nonstress tests or biophysical profiles may be initiated in the third trimester, particularly if growth restriction is identified or blood pressures are elevated.
• Earlier delivery planning. Even without new complications, delivery is often planned earlier than it would be for a first-time, low-risk pregnancy. If hypertension or features of preeclampsia develop, delivery timing will be revisited.

If you have not been referred to a maternal-fetal medicine (MFM) specialist, ask whether a consultation is appropriate. A history of severe or early-onset preeclampsia is a common reason for MFM co-management.

Risk factors you can change

Several factors that raise preeclampsia risk are within your control:

• Pre-pregnancy weight. Obesity is one of the strongest modifiable risk factors for preeclampsia. Even modest weight reduction before pregnancy lowers risk.
• Blood pressure control. If you have chronic hypertension, optimal control before and during early pregnancy is important. Talk with your provider about which medications are safe in pregnancy before you conceive if possible.
• Underlying conditions. Pre-pregnancy optimization of diabetes, kidney disease, lupus, and antiphospholipid antibody syndrome reduces risk. A prepregnancy visit can be high-yield for anyone with these conditions.
• Interpregnancy interval. Very short intervals (less than 18 months between delivery and the next conception) have been associated with higher preeclampsia risk in some studies. When timing allows, an interval of 18 to 24 months is generally preferred.

Warning signs to take seriously

Knowing the warning signs of preeclampsia matters more when you have had it before. Call your provider, or go to the nearest labor and delivery unit or emergency department, if you experience any of the following:

• A persistent or severe headache that does not resolve with acetaminophen.
• Visual changes, including blurring, flashing lights, or sudden vision loss.
• Pain in the upper right abdomen or shoulder.
• Sudden or rapid swelling of the face, hands, or feet.
• Difficulty breathing.
• Home blood pressure readings of 140/90 or higher on two readings taken at least four hours apart, or any single reading of 160/110 or higher.

These symptoms require same-day evaluation. Do not wait to see if they pass.

Postpartum still counts

Preeclampsia can develop or worsen in the days and weeks after delivery. Postpartum preeclampsia can occur up to six weeks after birth, and the warning signs are the same. Continue your home blood pressure monitoring through the postpartum period as your provider recommends, and report any of the symptoms above promptly. The Preeclampsia Foundation produces excellent patient resources on postpartum awareness if you want a printable checklist for your partner or family.

Why Preeclampsia Awareness Month matters for your next pregnancy

May is the moment many advocacy organizations, clinicians, and survivors point at the same problem at the same time. For someone going into a pregnancy after preeclampsia, awareness translates into action: starting low-dose aspirin on time, knowing your blood pressure cuff and how to use it, naming the warning signs out loud with the people who live with you, and confirming the monitoring plan with your provider before symptoms ever appear.

The bigger picture

Your history with preeclampsia is information, not a verdict. Low-dose aspirin, attentive monitoring, and a care team that knows your history change the trajectory meaningfully. Most people with a prior history of preeclampsia, even severe preeclampsia, go on to have uncomplicated subsequent pregnancies. The point of the additional oversight is not to magnify anxiety. It is to catch problems early, when options are greatest.

If you have not yet had a preconception or early-pregnancy conversation with your provider about aspirin, your monitoring plan, and warning signs, that conversation is the highest-yield thing you can do this Preeclampsia Awareness Month.

References

1. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 222: Gestational Hypertension and Preeclampsia. Obstet Gynecol. 2020;135(6):e237-e260. doi:10.1097/AOG.0000000000003891
2. American College of Obstetricians and Gynecologists, Society for Maternal-Fetal Medicine. Practice Advisory: Low-Dose Aspirin Use for the Prevention of Preeclampsia and Related Morbidity and Mortality. December 2021. Available at: acog.org/clinical/clinical-guidance/practice-advisory
3. Rolnik DL, Wright D, Poon LC, et al. Aspirin versus placebo in pregnancies at high risk for preterm preeclampsia. N Engl J Med. 2017;377(7):613-622. doi:10.1056/NEJMoa1704559
4. Bramham K, Briley AL, Seed P, et al. Adverse maternal and perinatal outcomes in women with previous preeclampsia: a prospective study. Am J Obstet Gynecol. 2011;204(6):512.e1-512.e9. doi:10.1016/j.ajog.2011.02.014
5. Society for Maternal-Fetal Medicine (SMFM). SMFM Consult Series #52: Diagnosis and management of fetal growth restriction. Am J Obstet Gynecol. 2020;223(4):B2-B17. doi:10.1016/j.ajog.2020.05.010
6. Preeclampsia Foundation. May is Preeclampsia Awareness Month. preeclampsia.org/awarenessmonth

This article is for informational purposes only and is based on evidence-based guidelines from organizations including the American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM). It is not a substitute for personalized guidance from your healthcare provider. Every pregnancy is unique. If you have questions or concerns about your health or your baby's wellbeing, please reach out to your care team. In an emergency, call 911 or go to your nearest emergency department.