Hypertension is known as the “silent killer” due to its tendency to not show any symptoms till it causes serious adverse effects on your health. If left untreated, it can cause several complications like heart disease, stroke, organ damage, etc. Are the complications of high blood pressure in pregnancy much worse? What causes this increase in blood pressure during pregnancy? In this article, we discuss how high blood pressure can affect the health of the mother-to-be and the unborn child, as well as the management and prevention of pregnancy-induced hypertension.Contents:
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:
All of these conditions were previously referred to as pregnancy-induced hypertension, which does not distinguish between chronic and gestational 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.
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.
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
Blood Pressure Readings
Low Blood Pressure
< 90/60 mmHg
Normal Blood Pressure
90/60 to 120/80 mmHg
140/90 to 149/99 mmHg
150/100 to 159/109 mmHg
≥ 160/110 mmHg
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.
The following are the risk factors for high blood pressure during pregnancy.
Along with the risk factors mentioned above, kidney, liver, and other organ disorders, and pre-existing hypertension can also contribute to preeclampsia.
The symptoms of high blood pressure in pregnancy are very similar to the symptoms of hypertension in non-pregnant populations. They include:
Preeclampsia can cause symptoms such as:
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.
Your healthcare provider will recommend the following measures to manage high blood pressure during pregnancy.
The pregnancy complications caused by high blood pressure can be divided into two categories based on who they affect. They are:
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.
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.
High blood pressure during pregnancy can increase the chances of miscarriage, i.e. loss of pregnancy before the 20th week of gestation.
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.
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.
High blood pressure during pregnancy, with or without preeclampsia, can cause damage to the liver, kidneys, brain, eyes, and other vital organs.
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.
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.
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.
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.
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.
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.
Consult a doctor or your healthcare provider immediately if you experience any of the symptoms of high blood pressure or preeclampsia mentioned below.
This World Heart Day, learn how to take care of your heart by controlling your BP. Why? Globally, heart disease is the leading cause of death and it could be linked directly to your blood pressure.Read Now
Ever wondered if BP measured at home is an accurate indicator of your condition? Here is why home BP measurement is a good idea.Read Now