Blood pressure monitoring takes on critical importance during pregnancy. Elevated blood pressure can develop during pregnancy even in women with no previous history of hypertension, potentially leading to serious complications for both mother and baby. Understanding what blood pressure readings mean during pregnancy, recognising warning signs, and knowing when to seek help empowers expectant mothers to protect their health and their baby's wellbeing.
Blood Pressure Changes During Pregnancy
Pregnancy causes significant changes in your cardiovascular system. Blood volume increases by 30-50% to support the growing baby, and hormonal changes affect blood vessel tone. These adaptations typically cause blood pressure to drop slightly during the first and second trimesters before returning to pre-pregnancy levels in the third trimester.
A normal blood pressure during pregnancy is generally considered to be below 120/80 mmHg. Readings between 120-129/80-84 mmHg are elevated and warrant monitoring. Blood pressure of 140/90 mmHg or higher during pregnancy is classified as high and requires medical attention.
Your healthcare team will check blood pressure at every prenatal visit, as rising blood pressure can be an early warning sign of pregnancy complications. Many midwives and obstetricians also recommend home monitoring for women with risk factors or elevated readings.
Types of High Blood Pressure in Pregnancy
High blood pressure during pregnancy falls into several categories, each with different implications:
Chronic hypertension: High blood pressure that existed before pregnancy or develops before 20 weeks of gestation. Women with chronic hypertension require careful monitoring throughout pregnancy and may need medication to control their blood pressure safely.
Gestational hypertension: High blood pressure that develops after 20 weeks of pregnancy in women who previously had normal blood pressure. This condition often resolves after delivery but increases the risk of developing chronic hypertension later in life.
Preeclampsia: A serious condition characterised by high blood pressure plus signs of organ damage, typically affecting the kidneys. Preeclampsia can develop suddenly after 20 weeks and can progress rapidly, making it essential to recognise warning signs and seek prompt medical attention.
Chronic hypertension with superimposed preeclampsia: Women with chronic hypertension can also develop preeclampsia, requiring particularly careful monitoring and management.
Understanding Preeclampsia
Preeclampsia affects 2-8% of pregnancies and is a leading cause of maternal and fetal morbidity. The condition involves more than just elevated blood pressure; it represents a systemic disorder affecting multiple organs including the kidneys, liver, and blood clotting system.
Risk factors for preeclampsia include first pregnancy, carrying multiples, age over 35 or under 20, obesity, family history of preeclampsia, and certain medical conditions including chronic hypertension, kidney disease, and autoimmune disorders. However, preeclampsia can occur in women with no identifiable risk factors.
Warning signs of preeclampsia require immediate medical attention:
- Blood pressure of 140/90 mmHg or higher on two readings at least 4 hours apart
- Severe headaches that don't respond to paracetamol
- Visual disturbances including blurred vision, seeing spots, or light sensitivity
- Upper abdominal pain, particularly under the ribs on the right side
- Sudden swelling of face, hands, or feet
- Sudden weight gain (more than 1 kg per week)
- Decreased urine output
- Nausea or vomiting in the second half of pregnancy
If you experience any of these symptoms, contact your midwife or hospital immediately. Preeclampsia can progress quickly, and early intervention is crucial for the best outcomes.
Home Blood Pressure Monitoring During Pregnancy
Home blood pressure monitoring is particularly valuable during pregnancy, as it allows for frequent readings between prenatal appointments and helps detect rising blood pressure early. Your healthcare provider may specifically recommend home monitoring if you have risk factors for hypertensive disorders of pregnancy.
When monitoring at home during pregnancy:
Use a validated upper arm monitor: Upper arm monitors are recommended over wrist monitors for accuracy. Ensure your cuff size is appropriate, as arm circumference may change during pregnancy. Our blood pressure monitor comparison features validated devices suitable for pregnancy monitoring.
Follow proper technique: Sit with your back supported and feet flat on the floor. Rest for five minutes before measuring. Position your arm at heart level. Take two readings one minute apart and record both.
Monitor consistently: Take readings at similar times each day, typically morning and evening. Record all readings to share with your healthcare team.
Know your thresholds: Your midwife or obstetrician will advise on specific readings that should prompt you to contact them. Generally, readings of 140/90 mmHg or higher warrant immediate communication with your healthcare provider.
Managing Blood Pressure During Pregnancy
If you develop high blood pressure during pregnancy, your healthcare team will develop a management plan tailored to your situation. Treatment depends on the type and severity of hypertension and how far along you are in your pregnancy.
Lifestyle modifications: For mildly elevated blood pressure, lifestyle changes may be sufficient. These include reducing sodium intake, staying physically active as approved by your healthcare provider, getting adequate rest, and managing stress. However, some typical blood pressure reduction strategies, like significant weight loss, are not appropriate during pregnancy.
Medication: Some blood pressure medications are safe during pregnancy, while others should be avoided. If you were taking blood pressure medication before pregnancy, your doctor may need to switch to a pregnancy-safe alternative. Never stop or change blood pressure medication during pregnancy without medical guidance.
Increased monitoring: Women with hypertensive disorders of pregnancy typically have more frequent prenatal appointments and may undergo additional testing to monitor fetal wellbeing, including ultrasounds to assess fetal growth and blood flow studies.
Hospitalisation: Severe preeclampsia may require hospital admission for close monitoring and, in some cases, early delivery to protect the health of mother and baby.
After Pregnancy
Blood pressure typically returns to normal within weeks of delivery, but women who experienced hypertensive disorders of pregnancy face increased long-term cardiovascular risk. Having had preeclampsia doubles your lifetime risk of heart disease and stroke.
For this reason, ongoing blood pressure monitoring remains important after pregnancy. Regular checks with your GP, healthy lifestyle habits, and awareness of cardiovascular risk factors help protect your long-term health.
If you're planning future pregnancies after experiencing gestational hypertension or preeclampsia, discuss prevention strategies with your healthcare provider before conceiving. Low-dose aspirin started early in pregnancy may reduce preeclampsia risk for women at higher risk.
Supporting Your Pregnancy Health
Blood pressure monitoring is one component of comprehensive prenatal care. Attend all scheduled prenatal appointments, communicate openly with your healthcare team about any symptoms or concerns, and don't hesitate to seek help if something feels wrong. Pregnant women's instincts about their own health are often accurate and should always be taken seriously.
For home monitoring during pregnancy, choose a validated blood pressure monitor that provides accurate readings. Our personalised recommendation quiz can help you find the right device. Bring your monitor to prenatal appointments so your healthcare provider can verify its accuracy against their equipment.
With appropriate monitoring and prompt attention to warning signs, most hypertensive disorders of pregnancy can be managed successfully, protecting the health of both mother and baby.