Differences between pregnancy-induced hypertension and preeclampsia [Doctor-supervised]

What is pregnancy toxemia?

Until now, toxemia of pregnancy was defined as the presence of any of the following symptoms: high blood pressure, proteinuria, or swelling. Because these symptoms improve when the pregnancy ends, it was thought that the fetus and placenta were the cause, but as research has progressed, the definition of toxemia of pregnancy has changed and it is now called pregnancy-induced hypertension.

Since the name was changed to pregnancy-induced hypertension, the emphasis has been placed on hypertension among the symptoms, and the definition has changed accordingly. Even if swelling or protein in the urine is observed, if blood pressure is not high, it is not considered pregnancy-induced hypertension.

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The reason behind the change in name and diagnostic criteria from pregnancy toxemia to pregnancy-induced hypertension

In 1986, the Japan Society of Obstetrics and Gynecology defined preeclampsia as “a condition in which one or more of the following symptoms are present during pregnancy: hypertension, proteinuria, or edema, and these symptoms are not merely due to incidental complications of pregnancy, and which occurs between the 20th week of pregnancy and six weeks after the postpartum period.”

Until now, the three major symptoms of preeclampsia – high blood pressure, proteinuria, and edema – tend to subside when the pregnancy ends, so it was thought that preeclampsia was caused by toxic substances derived from the fetus or placenta.

However, as medical treatment and research have advanced, it has become clear that the cause of these symptoms is not fetal, but is related to abnormal blood vessel contraction due to damage to the vascular endothelium (the cells lining the innermost layer of blood vessels) and blood clotting due to a decrease in platelets.

For these reasons, it was determined that the cause of preeclampsia was not fetal, but was primarily high blood pressure, and the name was changed to “gestational hypertension.”

Since then, hypertension symptoms have been further subdivided. Hypertension present before pregnancy (or up to 20 weeks of pregnancy) is now classified as “pregnancy complicated by hypertension,” hypertension alone occurring by the 20th week of pregnancy is classified as “gestational hypertension syndrome,” and hypertension and proteinuria are classified as “preeclampsia.”

Since 2018, even if there is no proteinuria, conditions such as liver or kidney dysfunction, neurological disorders, blood coagulation disorders, placental insufficiency, and fetal growth restriction are also classified as preeclampsia.

“Swelling” is not a symptom of pregnancy-induced hypertension

Before pregnancy-induced hypertension, when pregnancy was called toxemia, one of the three major symptoms was “swelling (edema).” However, swelling is a symptom that is seen in more than 30% of pregnant women. Even if the mother experiences swelling symptoms, in many cases it is considered not to have any effect on the fetus, and swelling has been excluded from the diagnostic criteria for pregnancy-induced hypertension.

Difference Between Preeclampsia and Pregnancy-Induced Hypertension

Preeclampsia was said to be caused by toxic substances originating from the fetus, resulting in high blood pressure, proteinuria, and swelling. It was called preeclampsia because the symptoms subsided after delivery and birth (the end of pregnancy), but it is now known that high blood pressure is the main cause.

The names and diagnostic criteria for pregnancy-induced hypertension have changed as follows:

• If proteinuria and swelling are present but there is no high blood pressure, it is not considered to be pregnancy-induced hypertension.
• If blood pressure rises after the 20th week of pregnancy and returns to normal after delivery, it is considered pregnancy-induced hypertension.
  • Mild: Systolic blood pressure (maximum blood pressure) 140mmHg or more/diastolic blood pressure (minimum blood pressure) 90mmHg or more
  • Severe: Systolic blood pressure (maximum blood pressure) 160mmHg or more/diastolic blood pressure (minimum blood pressure) 110mmHg or more
• If hypertension and proteinuria are present, the condition is classified as preeclampsia

What are the effects of pregnancy-induced hypertension on the baby?

When pregnancy-induced hypertension occurs, blood flow becomes poor. As a result, the fetus does not receive enough nutrients or oxygen, which can lead to fetal growth retardation. Caution is required as this can lead to premature birth, stillbirth, and low birth weight babies (weighing less than 2500g).

Characteristics of pregnant women at high risk of pregnancy-induced hypertension

Pregnant women who have high blood pressure, diabetes, or liver or kidney disease before pregnancy are said to be at higher risk of developing pregnancy-induced hypertension. In addition, obesity, advanced age, multiple pregnancies (twins, etc.), and first-time mothers may also be at higher risk, as well as those with a family history of high blood pressure or diabetes.

Causes of pregnancy-induced hypertension

As research into pregnancy-induced hypertension has progressed, it has become clear that the main causes are related to abnormal vascular contraction caused by vascular endothelial disorder and blood coagulation. However, although the pathology of preeclampsia is believed to be related to hypoxia and placental ischemia, the full cause has yet to be elucidated.

*Placental ischemia: Lack of sufficient blood flow to the placenta

Aggravation of pregnancy-induced hypertension and its symptoms

Pregnancy-induced hypertension is said to have few noticeable symptoms. However, it can lead to serious complications, so caution is required.

Eclampsia

If pregnancy-induced hypertension becomes severe, symptoms such as headaches, eye flickering, and numbness in the hands may occur. These are considered to be precursors to a condition called eclampsia, and if eclampsia does not subside, it can lead to loss of consciousness and cerebral hemorrhage, often putting both mother and child at risk for death.

If you are diagnosed with pregnancy-induced hypertension and experience symptoms such as headaches, it is important to see a doctor as soon as possible.

HELLP syndrome

HELLP syndrome is said to be caused by liver dysfunction due to a decrease in blood platelets. The main symptoms include abdominal pain (stomach pain), nausea, and vomiting. If it progresses, it can cause multiple organ failure, which can be life-threatening for both mother and child.

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If you are diagnosed with pregnancy-induced hypertension

If you are diagnosed with pregnancy-induced hypertension, you will most likely be treated as an outpatient if your symptoms are mild. You will be instructed by your doctor to recuperate at home and will be monitored regularly.

However, pregnancy-induced hypertension can suddenly become severe, so even if the symptoms are mild, you may be hospitalized at the doctor’s discretion.

Treatment for pregnancy-induced hypertension

There is no established cure for pregnancy-induced hypertension. It is important to review your lifestyle and rest. In severe cases of pregnancy-induced hypertension, medications to prevent convulsions and improve high blood pressure may be prescribed.

If the pregnancy-induced hypertension becomes severe and it is determined that there is a high risk to both mother and child, the pregnancy will be terminated and early induction of labour or a cesarean section will be performed.

Treatment costs for pregnancy-induced hypertension

Pregnancy is not an illness, so it is not covered by health insurance. However, pregnancy-induced hypertension is classified as an illness, so health insurance does apply. Also, some local governments provide subsidies for medical expenses, so it is important to check in advance.

For example, in Tokyo

• Households whose income tax amount for the previous year was 30,000 yen or less

or

• If the expected length of hospitalization is 26 days or more (if applying after discharge, the actual length of hospitalization is 26 days or more)

Subsidies are available for.

The availability and content of subsidies vary depending on the local government. If you are diagnosed with pregnancy-induced hypertension, be sure to check as soon as possible.

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Important things to know to prevent pregnancy-related hypertension

The detailed causes of pregnancy-induced hypertension have yet to be elucidated. Therefore, in order to prevent it, it is important to follow a diet and weight management to prevent high blood pressure, and to have regular prenatal checkups.

Eat a low-salt diet

Too much salt intake can raise blood pressure, so it is important to limit salt intake. The Ministry of Health, Labor and Welfare’s “Dietary Reference Intakes for Japanese” states that the target amount of salt intake for adult women is less than 6.5g per day. Be sure to review your diet and balance your nutrition to maintain your blood pressure.

Pay attention to weight management

Obesity and rapid weight gain can lead to pregnancy-induced hypertension. To ensure a healthy pregnancy and delivery, be sure to pay attention to your weight before pregnancy and maintain a well-balanced diet during pregnancy.

Be sure to get a prenatal checkup

Pregnancy-induced hypertension is said to have few noticeable symptoms. It may not be discovered until you have your prenatal checkups, so be sure to go for your regular checkups.

Pregnancy-induced hypertension can also lead to serious complications, putting both mother and child at risk for death. It is therefore important to review your diet and other lifestyle habits to stabilize your blood pressure.

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summary

Pregnancy-induced hypertension is a disease for which there is still no established treatment. Although there are few noticeable symptoms, if it becomes severe it can be a high risk for both mother and child, so be sure to have regular prenatal checkups and review your dietary habits that can lead to obesity and high blood pressure even before pregnancy.

Prenatal checkups are important for a healthy pregnancy and birth, including the early detection of pregnancy-induced hypertension. However, ultrasound examinations performed during prenatal checkups are not good at detecting congenital disorders caused by chromosomal abnormalities in the fetus.

At Hiro Clinic NIPT , we perform NIPT (new type prenatal diagnosis) for those who have confirmed pregnancy by ultrasound examination . NIPT (new type prenatal diagnosis) is a test that can determine the risk of congenital diseases caused by chromosomal abnormalities in the fetus by only taking a maternal blood sample.

Hiro Clinic NIPT has many doctors and staff members who are well versed in NIPT (new type prenatal testing) . If you have any questions about chromosomal abnormalities or NIPT (new type prenatal testing), please feel free to contact us.

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