Hypertension During Pregnancy

 

Hypertension During Pregnancy

 

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> Background:-

•        Hypertension can develop during pregnancy or can be pre-existing.

•        Although many pregnant women with high blood pressure have healthy babies without serious problems.

•        High blood pressure can be dangerous for both the mother and the fetus.

•        Women with pre-existing high blood pressure are more likely to have certain complications during pregnancy that those with normal BP.

 

What are the effects of hypertension in pregnancy?

•        The effects of high blood pressure range from mild to severe.

•        High blood pressure can harm the mother's kidneys and other organs, and it can cause low birth weight and early delivery.

•        In the most serious cases, the mother develops "toxemia of pregnancy" which can threaten the lives of both the mother and the fetus.

•        Toxemia of pregnancy is a common name used to describe preeclampsia and eclampsia.

•        Hypertensive disorders of pregnancy are one of the most common causes of death due to pregnancy (they resulted in 29,000 deaths in 2013).

Risk factors:-

•        Maternal related factors:

- Obesity (BMI ≥30) or age 35 years or more.

- Past history of hypertension or renal diseases.

- Adolescent pregnancy or new paternity.

•         Pregnancy related factors:

- Multiple gestation (twins or triplets, etc.).

- Placental abnormalities.

•        Family history related factors: 

- Family history of pre-eclampsia.

-African American race.

 

Most common types of hypertension during pregnancy:-

Mild Hypertension; 140-149/90-99 Moderate Hypertension; 150-159/100-109 Severe Hypertension: 160-more/110-more

1) Gestational Hypertension.

2) Pre-eclampsia.

3) Eclampsia.

4) Chronic Hypertension.

5) Superimposed Pre-eclampsia (chronic hypertension with preeclampsia).

 

1) Gestational Hypertension

•        Also known as pregnancy-induced hypertension (PIH).

•        Normal blood pressure before marriage.

•        Develops after 20 weeks of pregnancy.

•        BP more than or equal 140/90 mm Hg.

•        No proteinuria.

•        BP returns to normal after 12 weeks of delivery.

•        Some women with gestational hypertension eventually develop preeclampsia.

2) Pre-eclampsia (PE)

- Preeclampsia is a pregnancy complication characterized by high blood pressure and signs of damage to another organ system (often the kidneys). It is affects 2-8% of pregnancies worldwide.

Ø  Mild Pre-eclampsia :

•        Develops after 20 weeks of pregnancy.

•        BP more than or equal 140/90 mm Hg.

•        Proteinuria (≥ 300 mg/day).*

•        BP returns to normal after 12 weeks of delivery.

Ø  Sever Pre-eclampsia:

•        Develops after 20 weeks of pregnancy.

•        BP more than or equal 160/110 mm Hg.

•        Proteinuria (> 2-5 g/day).*

•        Thrombocytopenia (<100,000/microliter).*

•        Blurred vision and persistent headache.*

•        Sudden weight gain.*

•        Impaired kidney function (oliguria, ↑ creatinine levels).

•        Impaired liver function (↑ AST and ALT levels).*

•        Swelling (edema) particularly in face and hands.*

•        Pulmonary edema (shortness of breath).

•        BP returns to normal after 12 weeks of delivery.

•        Pre-eclamnsia, if untreated result in seizures at which point it is known as eclamnsia

 

 

 

 

3) Eclampsia

Ø  Eclampsia:-

•        Sever form of pre-eclampsia.

•        Eclampsia is considered a hypertensive crisis (Emergency).

•        Symptoms same as severe pre-eclampsia in addition to,

•        Onset of seizures (convulsions); tonic-clonic seizures.*

•        High proteinuria (> 5 g/day).*

•        Upper right abdominal pain.*

•        Possible Complications;*

  - Separation of the placenta (placental abruption).

  - HELLP syndrome; Hemolysis, Elevated Liver enzymes, Low Platelet count.

  - Premature delivery that leads to complications in the baby.

4) Chronic Hypertension

·         Hypertension was present before pregnancy.*

·         Not resolved after labour.*

·         Increase risk of developing preeclampsia (Superimposed Pre-eclampsia).

5) Superimposed Pre-eclampsia

·         Hypertension was present before pregnancy (chronic).*

·         Sudden increase in proteinuria and BP with decrease in platelet count.*

·         High risk for poor perinatal outcome and placental abruption.

Treatment of Hypertension During Pregnancy

 

 

Ø  Pre-pregnancy Advice:-

·         Stop antihypertensive treatment in women taking ACEIS, ARBS, Aliskiren or thiazides there is an increased risk of congenital malformation if these drugs are taken during pregnancy.

Ø   Nutritional Supplements:-

·         Do not recommend the following supplements only with the aim of preventing hypertensive during pregnancy;

-          Magnesium, folic acid, antioxidants (vitamins C and E), fish oils and garlic.

Ø   Prevention of Pre-eclampsia:-

·         Calcium: may be useful in populations with low calcium intake.

·         Low-dose aspirin (75 mg/day): from 12 weeks until birth, may have slight effect to reduce preeclampsia and adverse perinatal outcomes.

·         Bed rest or salt restriction: no evidence of benefit.

 

> Medications:-

·         Mild to moderate hypertension;

o   Methyldopa; is a drug of choice for control of mild to moderate hypertension in pregnancy, but it is a mild antihypertensive effect with a slow onset of action and associated fatigue.

o   Labetalol; is more rapid onset of action, may be given orally or parenterally, and is generally preferred as a first-line agent. 

o   Nifedipine; long acting is a reasonable medication to treat chronic

o   Hydralazine; (Oral), is effective as monotherapy or as add-on therapy to methyldopa in the long term management of chronic hypertension in pregnancy.

·         Severe hypertension; 

o   First-line medications;

- Hydralazine and labetalol (IV) have long been considered first-line drugs for the

    management of acute-onset and severe hypertension in pregnancy.

- Parenteral labetalol should be avoided in women with asthma or CHF. 

o   Second-line medications, if the first-line is failed;

- Sodium nitroprusside should be reserved for extreme emergencies and used for

   the shortest amount of time possible because of concerns about cyanide and

   thiocyanate toxicity in the mother and fetus or new-born.

·         Eclampsia seizures;

o   Magnesium sulfate remains the drug of choice for seizure prophylaxis in severe preeclampsia and for controlling seizures in eclampsia.

§  Dose; loading dose of 4 to 6 g given over 15 to 20 minutes, followed by a maintenance dose of 2 g/h as a continuous IV solution. 

§  Mechanism of action Mg 2+ is a unique Ca2+ antagonist as it can act on most types of calcium channels in vascular smooth muscle, may due it cause cerebral vasodilation, thus reducing ischemia generated by cerebral vasospasm during an eclamptic event.