Preeclampsia: Know the Numbers

How my home cuff caught mine

My home blood pressure cuff flagged my preeclampsia before anyone else did. This is what the condition is, who is at risk, how it is prevented and managed and the numbers to act on.

Key points

The American College of Obstetricians and Gynecologists (ACOG) treats a reading of 140/90 or higher as high blood pressure in pregnancy, and a top number of 160 or higher, or a bottom number of 110 or higher, as severe. Get both thresholds from your provider in writing, with what to do at each.
For anyone with one high-risk factor, the U.S. Preventive Services Task Force recommends 81 mg of aspirin a day after 12 weeks. Preeclampsia in a past pregnancy, twins, chronic high blood pressure, diabetes, kidney disease and autoimmune disease each count. Ask at your first visit.
Blood pressure follow-up needs to happen early after birth. ACOG recommends a check no later than 7 to 10 days for people with hypertensive disorders of pregnancy, and within 72 hours for those with severe hypertension. Book it before discharge and follow your home-monitoring plan. Warning symptoms need immediate care, not the next appointment.

My own blood pressure cuff is how I flagged the problem in my first pregnancy. Before the birth, it was diagnosed as gestational hypertension (high blood pressure that starts in pregnancy). After the birth, it became preeclampsia with severe features.

The timeline, from my records

In my third trimester. My first mild-range blood pressure reading in the office.

A few days later. My doctor wrote: “if you start seeing 140s/90s or above at home with or without discussed symptoms (headaches, right upper abdominal pain, vision changes that persist or any other changes), please come to triage or if unsure call the emergency line as previously provided.”

Over the following weeks. My readings at home climbed into the mild and then the severe range. Both times, I went to triage. Both times, my pressure was normal by the time they checked it, and my labs were normal. My chart records it this way: “Two triage visits for elevated BP mild and severe at home but normal in house.” My home readings captured elevations that weren’t showing up by the time I reached triage.

Near the end of the pregnancy, after midnight. I messaged my specialist: “I’ve gotten some higher blood pressure readings and wanted to flag them to you. Can you advise on what I should do?” Later that day I called the emergency line for advice.

Later that week. I had gained weight rapidly over two weeks, with significant swelling in my legs and face. The note: one more high reading “will be consistent with GHTN and delivery recommended at 37 weeks.” That’s gestational hypertension.

The induction. I was admitted for induction, for gestational hypertension.

The birth. The induction didn’t progress, and my baby was born by cesarean. After delivery, it became preeclampsia with severe features. I was on magnesium for 12 hours to protect against seizures, and went home on blood pressure medication.

During my first week at home. My pressure was up and I had chest pain. I called the hospital’s emergency line, as my discharge papers instructed, and then wrote to my doctor: “They mentioned to only call if blood pressures are 160/110. I noted that my discharge instruction say to call for BP 140/90 and will plan to keep calling until you confirm.” The reply said that if my readings were in the 150s, it sounded like I needed a higher dose. I was a new mother, recovering from surgery, trying to reconcile two numbers from the same hospital.

What preeclampsia is

What it is. Preeclampsia is a serious blood pressure condition of pregnancy. It usually develops after 20 weeks and involves high blood pressure, 140/90 or higher, along with protein in the urine or other signs that organs such as the kidneys or liver are affected. Early signs can include swelling and fluid retention. Some people feel completely fine. You don’t need a severe reading to seek care. Symptoms alone are reason enough.

Eclampsia and HELLP syndrome. When preeclampsia is severe enough to affect the brain, causing seizures or coma, it’s called eclampsia. The magnesium I was given after delivery is used to prevent and treat those seizures. HELLP syndrome is a serious complication in which preeclampsia damages the liver and red blood cells and interferes with blood clotting. Other serious complications include stroke, and for the baby, placental abruption (the placenta separating from the uterus too early), premature birth and low birth weight. Untreated, preeclampsia can be fatal for both parent and baby.

What causes it. The cause isn’t settled. Some researchers believe it comes from a problem with the blood supply to the placenta. Stress isn’t a direct cause.

Who’s at higher risk. The U.S. Preventive Services Task Force sorts risk factors into two groups:

High risk (one is enough)

Preeclampsia in a past pregnancy, especially with a bad outcome
Carrying twins or more
Chronic high blood pressure
Type 1 or type 2 diabetes before pregnancy
Kidney disease
Autoimmune disease, such as lupus or antiphospholipid syndrome

Moderate risk

First pregnancy
Obesity (body mass index over 30 before pregnancy)
Mother or sister had preeclampsia
Being Black
Lower income
Age 35 or older
A past low birth weight baby or bad pregnancy outcome, or more than 10 years since your last pregnancy
Pregnancy through IVF

Separately from the two columns, the Task Force says people with more than one moderate-risk factor may also benefit from aspirin.

Being Black is on that list for social reasons, not biological ones. In the Task Force’s words, the increased risk comes from “environmental, social, and historical inequities shaping health exposures, access to health care, and the unequal distribution of resources, not biological propensities,” and the disparities “largely result from historical and current manifestations of structural racism.”

Preventing it. For anyone with one high-risk factor, the Task Force recommends low-dose aspirin, 81 mg a day, starting after 12 weeks of pregnancy. People with two or more moderate-risk factors may also benefit, though the evidence is less certain. Cleveland Clinic puts the reduction in risk at about 15%, and says not to start aspirin unless your provider tells you to. Cleveland Clinic also suggests managing blood pressure and blood sugar, regular exercise and enough sleep. Aspirin lowers the risk. It doesn’t remove it, which is why monitoring matters.

How it’s managed.

Close monitoring: blood and urine tests for you, and ultrasounds and heart-rate checks for the baby.
Blood pressure medicine, including through an IV in the hospital.
Magnesium sulfate to prevent and treat seizures.
Delivery is a central treatment decision, but preeclampsia can persist, worsen or first appear after birth. Timing depends on gestational age and how you and your baby are doing. At 37 weeks, delivery is generally discussed; with severe features at 34 weeks or later, delivery is recommended after stabilization. Before 34 weeks, carefully selected stable patients may be monitored in the hospital and receive corticosteroids to help the baby’s lungs. If either patient’s condition worsens, delivery may be needed immediately.

What the numbers mean.

140 or higher on top, or 90 or higher on the bottom: High blood pressure in pregnancy. Call your care team.
160 or higher on top, or 110 or higher on the bottom: Severe range. Get assessed urgently.

It doesn’t end at delivery. Preeclampsia can appear for the first time after birth, and most late cases show up in the first 7 to 10 days, often with a headache. For people with high blood pressure in pregnancy, ACOG recommends a blood pressure check no later than 7 to 10 days after birth, and within 72 hours for those with severe hypertension.

It matters for the rest of your life. People who’ve had preeclampsia, especially early in pregnancy, have a greater risk later of heart disease, stroke and kidney disease, and of preeclampsia in a future pregnancy.

This pregnancy: prevention and monitoring

I’m overweight, and I’m pregnant again after having preeclampsia in my first pregnancy. That history puts me in the high-risk group.

With my clinician’s approval, I take low-dose aspirin this pregnancy: two 81 mg chewable tablets, 162 mg a day, as prescribed for me, in the orange-flavored kind (Bayer Chewable Low Dose Aspirin, 81 mg, Orange).

I had a hard time staying consistent with my medication. The orange chewables made it easier for me to take my dose.

I check and log my blood pressure at home, and act on the readings even when the office says I’m fine. I follow the thresholds in my written plan. A reading in the call range, I report. A reading in the severe range, or a warning symptom, means I go in rather than wait for a reply. When two instructions don’t match, I keep asking until they do.

Practical steps

Get the right cuff. Ask which home monitor and cuff size to use, and have someone check your technique. Ask whether your plan covers a monitor with a prescription; some plans, including some Medicaid plans, do.
Book the postpartum blood pressure check before you leave the hospital. Don’t wait for the six-week visit.
Tell everyone at home the warning signs, so someone else can recognize them if you’re too unwell to judge.
Ask who follows your blood pressure long term, after the postpartum check and into your next pregnancy.

Take this back

To discuss with your care team:

What is my individual risk, and what prevention is right for me?
Which cuff and size should I use, and who reviews my readings?
What findings would change the delivery plan?
Who manages my blood pressure after discharge, and when is my next check?
Does the after-hours line have the same thresholds as my discharge papers?

To discuss with the people in your life: Do you know my numbers and the warning signs? If I’m too sick to judge, will you take me in?

Don’t wait if

Get seen promptly, during pregnancy or after birth, for a headache that won’t go away, vision changes, pain in the upper belly, swelling in your face or hands, trouble breathing or a reading in the severe range.

Next in the series: “Chest Pain in Pregnancy and After Birth”