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Pregnancy Bliss | Reproductive Health Hub

High Blood Pressure medication in Pregnancy

High blood pressure (hypertension) is one of the most common complications of pregnancy. How safe are the antihypertensives?

Methyl-dopa (Aldomet®) is one of the most common antihypertensives used in pregnancy. It has been around for many years. It is known to be safe.

"Beta-blockers" (ß-blockers) is a group of drugs also used commonly for the treatment of raised blood pressure (hypertension). These include propranolol (Inderal®), acebutolol (Sectral®), atenolol (Tenormin®), oxprenolol (Trasicor®) and labetalol (a partial beta-blocker). There are many others.

Overall, beta-blockers are regarded to be safe in pregnancy. There is a small possibility that long term use in pregnancy could cause intrauterine growth restriction but this is usually outweighed by the potential benefits. Use just before delivery has also been associated with the fall of blood sugar levels in the baby (neonatal hypoglycaemia). The paediatricians therefore need to be informed of the mother's use of these drugs so the appropriate surveillance on the newborn can be maintained.

Hydralazine: This is used only for short-term lowering of blood pressure, usually in late pregnancy. For this, it is known to be safe. Occasionally it has been associated with fall in platelet count in the newborn, but this spontaneously recovers in about two or three weeks.

Nifedipine: This belongs to a group of drugs known as calcium channel blockers. It is also used for short-term lowering of blood pressure in pregnancy and in cases of preterm labour, it is employed to try to suppress labour. For this, it is known to be safe. Regular or long term use in pregnancy should be avoided if possible, as safety for the fetus cannot be guaranteed. However, no adverse effects have been reported and benefits should always be weighed against potential risks. Adalat® is the most popular brand in the UK.

Other calcium channel blockers include Nimodipine (Nimotop®), Felodipine (Plendil®), Amlodipine (Istin®), Diltiazem (Tildiem®) and several others.

A group of popular anti-hypertensives are the ones known as "ACE-inhibitors". What about these in pregnancy?

Yes, ACE-inhibitors such as captopril (Capoten®), enalapril (Innovace®), Cilazapril (ACE inhibitors not used in pregnancyVascace®), lisinopril (Carace®, Zestril®), quinapril (Accupro®) and a few others are very effective anti-hypertensives. They are not used in pregnancy. In fact, any woman taking these who is planning to conceive should be weaned off them and put on something else (such as a beta blocker or methyl-dopa).

What about anti-hypertensive medications which contain diuretics. Can these preparations be used in pregnancy?

There is no simple answer to this question. However, if hypertension is part of the syndrome known as pre-­eclampsia, diuretics (alone or in combination) should not be used. This is because their "drying" effect could worsen the poor blood supply to the baby inherent in this condition.

Chronic hypertension is not associated with this problem. However, pre-eclampsia could superimpose itself on simple chronic hypertension. For this reason, it is probably best to avoid diuretics in pregnancy altogether, especially if their use is to be long-term. As regards their effect on the fetus, the common diuretics (bendrofluazide and frusemide) are probably safe, as there is no evidence of direct ill-effects on the baby.

In summary therefore, diuretics, alone or in combination, should not be used in pre-eclampsia as they can potentially do more harm than good. They can probably be used safely in uncomplicated chronic hypertension but better alternatives are usually available.

Does the above mean, where strongly indicated, diuretics can be used in pregnancy?

Yes. If the pregnant woman is in heart failure or has lung oedema (water on the lungs), diuretics are indispensable and should be used.

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