High Blood Pressure in Pregnancy


The pressure exerted by the circulating blood on the walls of blood vessels is called as Blood Pressure. During the phase of heart contraction, when the blood flows at high velocity and pressure, the pressure it exerts on walls of blood vessels is called as Systolic Blood Pressure. Whereas, during the phase of heart relaxation, the blood flows at slower pace and low pressures and is called as Diastolic Pressure. The mean arterial blood pressure is used to describe the average blood pressure in single cardiac cycle. The blood pressure is measured in millimeter of Mercury.

Blood Pressure Normal Range (mm)
Systolic B.P. (S) 100-140
Diastolic B.P.(D) 60-90
Mean Arterial B.P.



The blood pressure is measured with the help of a special device, Sphygmomanometer. It can be either digital or manual. To diagnose accurately, two readings of blood pressure at 6 hours apart should be considered.

Ideal way to measure Blood Pressure:


  • Patient should sit upright.
  • The sphygmomanometer should be placed at the level of heart.
  • The pressure cuff should occupy 2/3rd space of arm between shoulder and elbow.
  • The cuff should be appropriately tightened. Not too tight nor too loose.
  • The tube of cuff should be in the medial aspect of arm.
  • The blood pressure should be measured by both the radial artery palpation and Brachial artery auscultation with the help of stethoscope.
  • The patient should not have consumed tea or coffee within half hour of BP measurement.
  • The patient should have a good night sleep in previous night.

White coat hypertension- In some patients, the fear of hospital or doctor may cause stress and false high blood pressure measurements. However, their blood pressure at home measures normal. This phenomenon is called as white coat hypertension. In such situation, it is advisable to measure the BP after certain time, when the patient has become comfortable with hospital atmosphere or at home.

Blood Pressure in Pregnancy!

During pregnancy, there are many physiological adaptive changes in the mother’s body. The blood pressure in the first and third trimester remain in normal range, but under the influence of physiological changes, the blood pressure in second trimester is usually low.

In the first trimester, under the influence of Estrogen, Progesterone and Relaxin hormones, the blood vessels dilates resulting in increase in their capacity and decrease in total peripheral resistance, so that blood flows adequately to the growing fetus.


Around the beginning of second trimester, in the second wave of invasion of developing placenta, the fetal trophoblastic tissue invades the muscular layer of maternal basal blood vessels of uterine artery completely to form a low pressure placental apparatus. This high capacity, low pressure system remains unaffected by the maternal cardiac cycle to ensure the adequate and stable blood supply to the baby without any harm due to pressure changes. So the blood pressure in second trimester is lower.

However, with increase blood volume in third trimester, the blood pressure again resumes to normal levels.

Classification of High Blood Pressure in Pregnancy:

  • Pregnancy induced Hypertension (PIH), Pre-eclampsia, Eclampsia.
  • Chronic Hypertension.
  • Chronic hypertension with superimposed Preeclampsia.
  • Unclassified.


  • Pregnancy Induced Hypertension: In pregnancy, when the blood pressure rises above 140/90 mm Hg after 20 weeks of gestational age. It usually subsides within 6 weeks post delivery.
  • Pre-eclampsia: As a result of high blood pressure, when the endothelial layer of kidney is damaged resulting in loss of proteins in urine and subsequent low albumin levels in blood leading to edema.
  • Eclampsia: When the blood pressure rises to alarmingly high levels resulting in brain edema, convulsions and unconsciousness.


  • Chronic Hypertension: When the hypertension exists preconception or it develops in first 20 weeks of gestation or it persist even after 6 weeks post delivery.
  • Chronic Hypertension with superimposed Preeclampsia: When the mother suffering from Chronic hypertension have worsening of symptoms, increased loss of albumin in urine or uncontrolled hypertension.

Cause of Pregnancy Induced Hypertension:

The exact cause of Pregnancy Induced Hypertension is not known. However the most popular hypothesis blames abnormal placenta formation and defective hormonal levels as its cause.

In around 10 percent of pregnancies, there is defective second wave of invasion resulting in abnormal placenta formation. The placental blood vessels remain responsive to mother’s cardiac cycle and blood pressure changes resulting in high peripheral resistance. Consequently, there is sufficient blood supply to baby during cardiac contraction, but poor & compromised blood supply in cardiac relaxation phase.

To ensure the optimum blood supply to baby against high peripheral resistance, the mother’s blood pressure rises to abnormal high levels resulting in Pregnancy Induced Hypertension.

Side effects of High Blood Pressure on Mother:

High blood pressure adversely affects all the organs of the body.

  • Swelling in brain resulting in severe headache, blurring of vision, blindness, convulsion, intracranial hemorrhage, paralysis etc.
  • Heart failure.
  • Swelling in lungs causing breathlessness, poor oxygenation etc.
  • Hemolytic anemia.
  • Swelling and dysfunction of kidneys causing acute and chronic kidney disease.
  • Liver dysfunction causing jaundice, elevated liver enzymes, itching all over body, indigestion etc.
  • HELLP – Hemolysis, Elevated Liver enzymes, Low Platelets.
  • Separation of placenta from its bed (Abruptio placenta).
  • Increased post delivery bleeding (Post partum hemorrhage-PPH).
  • Dysfunction of coagulation cascade resulting in Disseminated Intravascular coagulation (DIC), a fatal consumptive coagulation disorder which can result in bleeding in any part of body even with trivial trauma.

Prodromal Symptoms of  Impending Eclampsia:

  • Severe headache.
  • Blurring of vision, aura.
  • Persistent vomiting.
  • Pain in upper right quadrant of abdomen due swelling in liver capsule.


When the blood pressure shoots up to abnormally high levels causing brain edema and consequent convulsions or unconsciousness, the condition is called Eclampsia.

First aid during convulsions:

  • Make the patient comfortably lie down on couch or cleared floor.
  • Do not attempt to keep them erect. Lying down position negates the effect of gravity and improves the blood supply to brain. Also, the risk of fall & injury decreases.
  • Loosen the cloths. During convulsion, involuntary muscle movements produce more heat and increase body temperature, so loosening cloths may help to regulate it.
  • Remove spectacles to avoid injury with glass break.
  • Do not splash water on face.
  • Avoid giving oral medicines or water during convulsion to prevent aspiration.
  • Do not gather crowd around the patient. Clear the space to allow free flow of fresh air.
  • If somebody can help the patient rescue position or jaw thrust, as shown in video, it would prevent aspiration and tongue bite. However, do not forcefully open the closed mouth. It may harm further.
  • Allow the patient to take rest and do not excite them to avoid stress.
  • Try to seek the immediate medical help at the earliest.

Side effects of High blood pressure on baby:

  • Utero-placental insufficiency causing Fetal Intrauterine Growth Retardation (IUGR).
  • Low birth weight.
  • Sudden intrauterine fetal death.

Management of High Blood Pressure in Pregnancy:

  • Strict bed rest or hospitalization as advised by the Doctor.
  • Restrict salt intake up to maximum 4 grams/day.
  • Take high protein and calcium rich diet.
  • Avoid junk, oily and very spicy food.
  • Timed delivery at an appropriate gestational age when it is safe for both mother and baby.
  • In case where preterm delivery is anticipated, it is advisable to give corticosteroid injections of Betamethasone to accelerate fetal lung maturity, so that the newborn is able to breathe properly.
  • Take the prescribed medicines sincerely at appropriate doses and schedule.
  • The only treatment of uncontrolled blood pressure, eclampsia, DIC or HELLP syndrome is to deliver the baby at the earliest to save the life of mother.


  • Preferably plan your delivery in a well equipped tertiary center with good ICU and NICU facilities.
  • It is advisable to deliver the term baby (37 completed weeks of gestation) as much as possible.
  • In case of uncontrolled high blood pressure or life threatening conditions such as Eclampsia, DIC, HELLP syndrome etc. the only treatment is to deliver the baby at the earliest, irrespective of gestational age, to save the life of mother. However, the premature delivery has its own complications for the baby.
  • The decision to deliver the mother vaginally or by Cesarean delivery depends on many factors such as condition of mother and baby, urgency of delivery, expertise and availability of facilities etc.

Risk of Recurrence in next Pregnancy:

The risk of development of high blood pregnancy in subsequent pregnancies is as high as 30%.

It is not possible to absolutely prevent the occurrence of high blood pressure in pregnancy, but a good antenatal care and decision making can definitely reduce the risks and complications of Pregnancy and child birth & ensure safety of both the mother and baby!


The information is shared to create awareness towards Pregnancy and Childcare to reduce maternal and child deaths. Atmost care has been taken by the author to include the verified information from authentic sources. However, kindly discuss the same with your health care provider before implementation.