All You Need to Know About Hypertension in Pregnancy

What is Gestational Hypertension?

Hypertension is a condition characterised by systolic blood pressure levels of 140 mmHg or above and/or diastolic blood pressure levels of 90 mmHg or above. Untreated or uncontrolled high blood pressure levels can damage your blood vessels and lead to several complications.

Gestational hypertension is defined as high blood pressure levels (≥140/90 mmHg) in pregnancy, in women who have never been diagnosed with elevated blood pressure levels earlier. It usually develops after 20 weeks of gestation (period of time between conception and childbirth). Gestational hypertension generally resolves by itself after childbirth, within a period of 12 weeks. Like hypertension, the symptoms of gestational hypertension are mild to non-existent in the initial stages and often go unnoticed. 

High blood pressure during pregnancy can cause risks to the health of both the mother-to-be and the unborn child, and increase the chances of complications during birth, birth defects in the baby, miscarriage, etc. Hypertension can damage the blood vessels in the placenta, which is an organ that supplies oxygen and nutrition to the unborn child. The placenta grows inside the amniotic sac, which is present in the uterus of a pregnant woman. The placenta is attached to the unborn child through the umbilical cord. The blood vessels in the placenta supply the child with oxygen and nutrition from the mother, which the child requires to grow. These blood vessels also carry the deoxygenated blood from the child to the mother. Uncontrolled hypertension can damage these blood vessels, resulting in reduced blood supply to the child.

In most pregnant women, blood pressure will fluctuate between the first, second, and third trimesters depending upon the hormones secreted during each trimester. These changes are usually minor and do not cause any symptoms or complications. However, complications arise when the blood pressure levels are persistently above 140/90 mmHg during the entirety or large periods of the pregnancy. 

According to the working report published by the National High Blood Pressure Education Program, which is a part of the National Institutes of Health (NIH), USA, high blood pressure disorders in pregnancy can be divided into the following categories:

1. Gestational hypertension
2. Chronic hypertension
3. Chronic hypertension with preeclampsia
4. Pre-eclampsia and eclampsia

All of these conditions were previously referred to as pregnancy-induced hypertension, which does not distinguish between chronic and gestational hypertension.

What is Chronic Hypertension?

Chronic hypertension in pregnancy is a condition where you have high blood pressure (≥140/90 mmHg) before conception or are diagnosed within the first 20 weeks of your pregnancy. Hypertension that does not resolve within 12 weeks of childbirth can also be grouped into this category. 

What is Preeclampsia?

Preeclampsia is defined  as high blood pressure levels in pregnancy along with elevated levels of protein in the urine. The high urine protein levels can be an indication of kidney damage. It usually develops after 20 weeks of gestation.

Preeclampsia can be a precursor to eclampsia, which is a pregnancy complication that causes seizures before, during, or after delivery. Eclampsia is a dangerous complication that can lead to coma or death.

What is the Normal Blood Pressure Range in Pregnancy?

The National Health Service (NHS) of the United Kingdom classifies blood pressure into the following categories according to the blood pressure readings.

Blood Pressure Range During Pregnancy

What Causes High Blood Pressure During Pregnancy?

The exact causes of high blood pressure during pregnancy are unknown, but one of them could be the increase in blood volume that occurs in pregnancy. This increase in the amount of blood can exert additional pressure on the walls of your blood vessels, resulting in elevated blood pressure levels. The normal blood volume is generally restored 6 to 8 weeks after childbirth.

What are the Risk Factors for Pregnancy-Induced Hypertension?

The following are the risk factors for high blood pressure during pregnancy.

• Being overweight or obese (having a body mass index (BMI) of over 25 kg/m2 )
• Lack of regular physical activity
• Being over the age of 35 years at the time of conception
• First-time pregnancy
• Being pregnant with more than one child
• Having Type 1 Diabetes or Type 2 Diabetes
• Smoking or tobacco consumption
• Alcohol consumption
• Having a family history of hypertensive disorders during pregnancy
• Having autoimmune disorders
• The use of fertility procedures like in vitro fertilisation (IVF)

Along with the risk factors mentioned above, kidney, liver, and other organ disorders, and  pre-existing hypertension can also contribute to preeclampsia.

What are the Symptoms of High Blood Pressure in Pregnancy?

The symptoms of high blood pressure in pregnancy are very similar to the symptoms of hypertension in non-pregnant populations. They include:

• Headaches
• Nosebleeds
• Fatigue or tiredness
• Chest pain
• Heart palpitations or pounding heartbeat
• Issues with your vision
• Confusion or irritability

Preeclampsia can cause symptoms such as:

• Nausea and/or vomiting (after the second trimester)
• Severe and persistent headaches
• Shortness of breath or trouble breathing
• Swelling in the face, hands, and feet
• Upper abdominal pain, especially on the right side
• Blurred or spotty vision

How is Hypertension in Pregnancy Diagnosed?

As high blood pressure does not show any symptoms in the initial stages, hypertension in pregnancy is most often diagnosed during prenatal visits (check-ups during pregnancy) to the doctor. Your healthcare provider will be able to detect elevated blood pressure levels using a sphygmomanometer or a BP monitor. You can do the same by measuring your blood pressure at home, however, the official diagnosis must be made by a doctor.

Your healthcare provider may also run urine tests to detect the presence of proteins in your urine, in order to detect preeclampsia. Other tests including blood and urine screening, ultrasound imaging, etc. are performed during prenatal visits to monitor the health of the mother-to-be and the development of the unborn child. These tests can also detect other conditions like gestational diabetes, Rh (rhesus) incompatibility, nutritional deficiencies, birth defects in the foetus, etc.

How is Gestational Hypertension Treated or Managed?

Your healthcare provider will recommend the following measures to manage high blood pressure during pregnancy.

• Medication to lower blood pressure levels
• A low sodium diet or DASH diet
• Regular physical activity and exercise as advised by your doctor
• Good quality sleep for at least 7 to 9 hours a day
• Meditation, breathing exercises, or other relaxation techniques to manage stress
• Quitting smoking
• Avoiding caffeine and alcohol

What are the Complications of Hypertension in Pregnancy?

The pregnancy complications caused by high blood pressure can be divided into two categories based on who they affect. They are:

Complications in pregnant women

• Placental abruption

The condition where the placenta detaches from the wall of the uterus (womb). This can result in excessive bleeding in the mother and oxygen deprivation in the child.

• Stroke or heart attack

High blood pressure can damage the arteries that supply blood to the brain and heart. This can lead to the build-up of plaque (accumulation of cholesterol, calcium, cell debris, etc.) in the linings of the inner walls of these blood vessels. Plaque can cause arteries to become stiff, narrow, and clogged. Narrowed arteries can lead to reduced blood flow to the brain or heart tissue, resulting in a stroke or a heart attack, respectively.

• Miscarriage

High blood pressure during pregnancy can increase the chances of miscarriage, i.e. loss of pregnancy before the 20th week of gestation.

• Postpartum haemorrhage (PPH)

Postpartum haemorrhage or bleeding is defined as excessive bleeding (of up to 1000 ml of blood loss) that occurs in women within 24 hours of giving birth. High blood pressure and preeclampsia increase the risk of PPH in pregnant women.

• Pulmonary oedema

High blood pressure during pregnancy and preeclampsia can lead to the accumulation of fluid in the lungs of the pregnant woman. This can cause shortness of breath due to reduced oxygen supply.

• Organ damage

High blood pressure during pregnancy, with or without preeclampsia, can cause damage to the liver, kidneys, brain, eyes, and other vital organs.

• Eclampsia

A condition that causes seizures in women during pregnancy or just after childbirth. Preeclampsia is the primary risk factor for eclampsia. In rare cases, eclampsia can cause brain damage, coma, or death if left untreated.

• HELLP syndrome

This condition is characterised by haemolysis (breakdown of red blood cells), elevated liver enzymes (indicative of liver disorders), and low platelet (helps in forming clots) count. HELLP syndrome can be caused by preeclampsia, and can be life-threatening without immediate medical assistance.

Complications in unborn children

• Preterm or premature birth

Occurs when the child is born too early (before 37 weeks of gestation). Depending on how early the child is born it can experience several complications like low body temperature, immature or partially developed organs (especially lungs), poor suckling and swallowing reflexes which can lead to difficulty in feeding, etc.

• Low birth weight and growth restriction

Occur when the child is born underweight due to reduced blood supply during gestation. Poor blood supply during growth results in the child getting fewer nutrients, which hampers their growth and development, especially fat storage.

• Birth defects

Studies have shown that women who have hypertension during pregnancy have a higher risk of having a child with birth defects like structural malformations in the heart or neural tube (the precursor to the child’s spinal cord, spine, brain, and skull) defects.

• Death

Foetal death or stillbirth can occur anytime after 20 weeks of gestation, caused by a lack of oxygen and nutrient supply to the child. Neonatal death can occur within the first 28 days of the child’s life, due to preterm birth, respiratory problems, birth defects, etc.

How to Prevent High Blood Pressure During Pregnancy?

• Keep your weight in check.

  Obesity is a preventable risk factor for hypertension. Weight gain is normal in pregnancy, but if you are concerned that you have gained too much weight, consult your doctor or a nutritionist.

• Exercise regularly

   Though intensive physical activity may not be possible or advisable in the second and third trimesters, light to moderate exercise like walking, yoga, swimming, etc. can help keep your blood pressure low.

• Eat a balanced and nutritious diet

  Diet is a crucial part of keeping your blood pressure normal. Consult a nutritionist or seek advice from your doctor to make sure you are receiving all the correct amounts of nutrients you and your unborn child need. A nutritionist can also make sure you are consuming a diet that will not elevate your blood pressure.

• Practice relaxation techniques to manage stress

   You may undergo several physical and physiological (hormonal) changes during pregnancy, which can cause stress. Stress can have several adverse effects on your body during pregnancy, high blood pressure being one of them. Breathing exercises, yoga, meditation, etc. can help you handle stress in a healthy way.

• Get quality sleep

  Aim to get at least 7 to 9 hours of sleep every night to maintain normal blood pressure levels. Some studies have shown that afternoon naps that range from 20 to 40 minutes can also have a positive effect on your blood pressure and the birthweight of your unborn child.

• Stop smoking

  The nicotine and carbon monoxide in tobacco can raise your blood pressure levels, and are also bad for the health of your unborn child. Thus quitting can decrease your blood pressure levels and improve your overall health.

• Avoid alcohol and caffeine

   Both alcohol and caffeine can have a negative effect on the growth and development of your child. They also cause your blood pressure to rise. Thus avoiding alcohol and foods that contain high amounts of caffeine during your pregnancy can help you maintain normal blood pressure levels.

• Monitor your blood pressure regularly

   Checking your blood pressure regularly can help you detect any variations in your blood pressure in the initial stages, which makes the prevention or management of high blood pressure in pregnancy more effective.

When to See a Doctor?

Consult a doctor or your healthcare provider immediately if you experience any of the symptoms of high blood pressure or preeclampsia mentioned below.

• Severe and persistent headaches that have not resolved with medication
• Pain in the upper right abdominal area
• Persistent nausea or vomiting (after the second trimester)
• Difficulties in breathing
• Sudden weight gain
• Swelling of the hands and face.