Gestational Hypertension

What gestational hypertension is

During a healthy pregnancy, blood pressure dips in the first half and returns to normal near term. In gestational hypertension, blood pressure rises above 140/90 mm Hg for the first time after 20 weeks. The cause is thought to involve how the placenta implants and how blood vessels adapt to pregnancy, the same process that underlies preeclampsia, but less advanced.

For an overview of all blood pressure problems in pregnancy, see pregnancy-induced hypertension.

Blood pressure readings in pregnancy

Either number counts: a top (systolic) reading of 140 or a bottom (diastolic) reading of 90 is enough.

Gestational hypertension vs preeclampsia and chronic hypertension

If blood pressure is still high 12 weeks after delivery, the diagnosis is changed to chronic hypertension.

Symptoms

Gestational hypertension itself usually has no symptoms and is found at a routine prenatal visit. That is why every visit includes a blood pressure check. Symptoms such as headache, vision changes, upper belly pain, sudden swelling or shortness of breath suggest that preeclampsia may be developing and need same-day assessment.

Risk factors

• First pregnancy
• Obesity (BMI 30 or more)
• High blood pressure, preeclampsia or gestational hypertension in a past pregnancy
• Twins or more
• Age 35 or older
• Pre-existing diabetes, kidney disease, lupus or antiphospholipid syndrome
• IVF pregnancy
• Black race, which reflects higher rates of hypertension and unequal care, not biology alone

Monitoring and diagnosis

Once diagnosed, you can expect:

• Blood pressure checks once or twice a week, and often home monitoring with a validated cuff
• Urine tests for protein (a protein-to-creatinine ratio or 24-hour collection)
• Blood tests for platelets, liver enzymes, kidney function and sometimes uric acid
• Ultrasound every 3 to 4 weeks to check the baby's growth and fluid, plus non-stress tests
• Symptom checks at every visit for signs of preeclampsia

Treatment

Mild gestational hypertension

Blood pressure between 140/90 and 159/109 mm Hg is usually managed with close monitoring as an outpatient. Many clinicians start medication if readings stay at 140/90 or above, following recent evidence that treating mild hypertension in pregnancy reduces complications. Common choices are labetalol, nifedipine and methyldopa. ACE inhibitors, ARBs and some other blood pressure drugs are avoided in pregnancy because they can harm the baby.

Bed rest is not recommended: it does not improve outcomes and raises the risk of blood clots. Salt restriction below normal intake is also not advised.

Severe-range blood pressure

Readings of 160/110 or higher are treated urgently in the hospital with intravenous labetalol or hydralazine, or fast-acting oral nifedipine. Magnesium sulfate may be given to prevent seizures if preeclampsia with severe features is diagnosed.

Timing of delivery

Gestational hypertension alone does not mean a cesarean birth: most people can have an induced vaginal delivery.

Complications

• Progression to preeclampsia, eclampsia (seizures) or HELLP syndrome
• Placental abruption, when the placenta separates early
• Slower growth of the baby (intrauterine growth restriction)
• Preterm birth
• Stroke, in very severe uncontrolled hypertension

The earlier gestational hypertension appears, the higher the chance it progresses: when it starts before about 32 weeks, around half of cases go on to preeclampsia.

After birth

Blood pressure often peaks 3 to 6 days after delivery. Preeclampsia can even appear for the first time after birth, up to about 6 weeks later. A blood pressure check within 3 to 10 days of delivery is recommended. Medication is usually tapered and stopped over days to weeks. Labetalol and nifedipine are compatible with breastfeeding.

Long-term health

Gestational hypertension is an early warning for later heart disease. People who had it have a higher lifetime risk of chronic high blood pressure, heart disease, stroke and type 2 diabetes. Tell your primary care doctor, have your blood pressure checked at least yearly, and review cholesterol and blood sugar.

Lowering the risk in future pregnancies

• Low-dose aspirin taken daily from 12 to 16 weeks until delivery lowers the risk of preeclampsia for people at high risk. Take it only if your obstetric team recommends it.
• Reach a healthy weight and control blood pressure before conceiving.
• Get regular exercise during pregnancy if your provider agrees.

Frequently asked questions

What is the difference between gestational hypertension and preeclampsia?

Both are high blood pressure starting after 20 weeks. In gestational hypertension, there is no protein in the urine and no sign of organ involvement. Preeclampsia adds protein in the urine or signs that the kidneys, liver, blood, brain or lungs are affected. Gestational hypertension can turn into preeclampsia, so monitoring continues.

Why deliver at 37 weeks with gestational hypertension?

At 37 weeks the baby is full term, and continuing the pregnancy only raises the chance of preeclampsia and other complications without extra benefit to the baby. Studies show that inducing labor at 37 weeks for mild gestational hypertension improves outcomes for the mother without increasing cesarean rates.

Can gestational hypertension harm my baby?

Mild, well-monitored gestational hypertension usually has good outcomes. Risks rise if it becomes severe or progresses to preeclampsia, which can reduce blood flow through the placenta, slow growth and lead to early delivery. Ultrasound scans and fetal monitoring check that the baby is doing well.

Does gestational hypertension go away after delivery?

Yes, by definition it resolves within 12 weeks after birth, usually much sooner. Blood pressure can rise again in the first week, so postpartum checks are important. If it is still high after 12 weeks, it is reclassified as chronic hypertension.

Will I get gestational hypertension again in my next pregnancy?

The chance of high blood pressure in a later pregnancy is raised, with estimates ranging from about 1 in 5 to 1 in 2, especially if you developed it early or have other risk factors. Your provider may recommend low-dose aspirin and closer monitoring next time.