Hypertension in Pregnancy: When Is High Blood Pressure Dangerous, and How Is It Managed?
Assoc. Prof. Sezen Bağlan Uzunget, MD
Cardiologist
"My blood pressure was normal before pregnancy. Why is it rising now?"
"Could blood pressure medication harm my baby?"
"Will my blood pressure return to normal after delivery?"
High blood pressure during pregnancy is an important condition affecting both mother and baby. It may be present before pregnancy or develop for the first time during pregnancy.
Many pregnancies can progress safely with appropriate treatment and regular monitoring. However, high blood pressure must be assessed, particularly for the possibility of preeclampsia.
Which Blood Pressure Readings Are High During Pregnancy?
A systolic blood pressure of 140 mmHg or higher, or a diastolic blood pressure of 90 mmHg or higher, requires assessment for hypertension. An elevation in either number matters.
Diagnosis is based on correctly performed measurements, repeated when appropriate.
A systolic pressure of 160 mmHg or higher, or a diastolic pressure of 110 mmHg or higher, is severe hypertension and requires urgent assessment. Do not wait for a routine appointment at these levels.
What Are the Types of Hypertension in Pregnancy?
Chronic Hypertension
Hypertension known before pregnancy or usually identified before 20 weeks of pregnancy.
Gestational Hypertension
High blood pressure developing after 20 weeks of pregnancy, initially without evidence of the organ involvement associated with preeclampsia. Regular follow-up is necessary because preeclampsia may develop later.
Preeclampsia
A condition usually developing after 20 weeks in which hypertension may be accompanied by protein in the urine, impaired kidney or liver function, a low platelet count or other organ involvement.
Protein in the urine is not always required for a diagnosis of preeclampsia.
Preeclampsia can also develop in women who already have chronic hypertension.
Is Preeclampsia a Form of "Pregnancy Poisoning"?
Although this expression is sometimes used, preeclampsia is not caused by an external poison. It is a serious pregnancy-related condition that can affect blood vessels and several organs.
Potential risks include seizures, stroke and organ injury in the mother, and impaired growth or premature birth for the baby. Assessment therefore involves more than the blood pressure reading alone.
Which Symptoms Are Warning Signs?
The following symptoms during pregnancy or after delivery require prompt assessment:
- A persistent, severe or unusual headache
- Blurred vision, flashing lights or loss of vision
- Upper abdominal pain, especially beneath the right ribs
- New, significant shortness of breath
- Sudden, marked swelling of the face and hands
- A significant deterioration in general health
Preeclampsia can sometimes be detected without obvious symptoms. Feeling well does not remove the need for blood pressure checks.
How Is High Blood Pressure Monitored During Pregnancy?
Monitoring includes blood pressure, symptoms, and blood and urine tests. Kidney function, liver enzymes, platelet count and urine protein may be assessed.
The obstetric team also monitors the baby's growth and wellbeing. The frequency of follow-up depends on the type and severity of hypertension and the stage of pregnancy. Hospital monitoring may be necessary.
Can Blood Pressure Medication Harm the Baby?
Not all blood pressure medicines have the same safety profile in pregnancy. However, untreated high blood pressure can also place mother and baby at risk.
Labetalol, nifedipine or methyldopa may be used in suitable patients. Treatment depends on the mother's health, blood pressure and medication availability.
Certain medicines, including ACE inhibitors and angiotensin receptor blockers, should not be used during pregnancy. Women with hypertension should therefore have their medication reviewed before planning a pregnancy.
When pregnancy is discovered, current medications should be reviewed promptly with a healthcare professional. Treatment should not be changed independently.
Is Aspirin Used to Prevent Preeclampsia?
Low-dose aspirin may be recommended for some pregnant women at increased risk of preeclampsia. Starting from 12 weeks of pregnancy is commonly considered.
Not every pregnant woman needs aspirin, and it does not replace blood pressure medication. The clinician supervising the pregnancy should determine the dose and when to start and stop treatment.
Does Every Pregnant Woman with Hypertension Need an Early Delivery or Caesarean Birth?
No. Hypertension does not mean that every pregnancy requires the same delivery plan.
The timing and mode of delivery depend on the stage of pregnancy, blood pressure control, the presence of preeclampsia, maternal organ function and the baby's condition. When serious features develop, earlier delivery may be necessary for the safety of mother and baby.
Does the Risk End Immediately After Delivery?
No. Blood pressure may remain high after birth or rise for the first time.
Preeclampsia can develop during the first six weeks after delivery, even in women whose blood pressure was normal throughout pregnancy. Severe headache, visual changes or breathlessness during this period should not be dismissed as normal postpartum symptoms.
Medication is adjusted with breastfeeding in mind. Blood pressure monitoring and follow-up should continue after discharge.
Can Hypertension in Pregnancy Affect Future Heart Health?
A history of hypertension in pregnancy or preeclampsia is associated with an increased risk of hypertension and cardiovascular disease later in life.
Always mention this history at future medical appointments. Follow-up should not end as soon as blood pressure returns to normal. Long-term assessment should also consider blood pressure, weight, blood glucose and cholesterol.
When Should You Seek Emergency Help?
During pregnancy or after delivery, a systolic pressure of 160 mmHg or higher, or a diastolic pressure of 110 mmHg or higher, requires urgent assessment. An elevation in either number is sufficient.
For severe headache, loss of vision, chest pain, significant breathlessness, seizures or altered consciousness, call emergency medical services immediately—112 in Türkiye.
This content is provided for general educational purposes. The diagnosis and treatment of hypertension in pregnancy and delivery planning should be individualized by the obstetric team, with cardiology and other specialists involved when appropriate.
Sources
- NICE NG133: Hypertension in Pregnancy—Diagnosis and Management
- 2025 ESC Guidelines on Cardiovascular Disease and Pregnancy
- ACOG: Preeclampsia and High Blood Pressure During Pregnancy