Long QT syndrome and pregnancy

Long QT syndrome

If you are planning a pregnancy, please try to discuss this with your cardiologist before you become pregnant.

Pregnancy is usually uncomplicated in women with long QT syndrome (LQTS), but your cardiologist may recommend repeating your cardiac tests, so that these are up-to-date before your pregnancy.

If the genetic cause of your LQTS is known, you may wish to discuss assisted conception such as in-vitro fertilisation (IVF) with pre-implantation genetic testing (PGT). This avoids passing the faulty gene to your children.

If you do become pregnant you should continue to take your beta blocker medicine and contact your cardiologist or the inherited cardiac conditions nurses.

Beta blockers

Beta blockers are considered safe in pregnancy. If you have been prescribed a beta blocker to reduce your risk of serious heart rhythm abnormalities you should continue to take this throughout pregnancy and after you have given birth.

  • During pregnancy your blood volume increases and so the dose of your beta blocker may need to be changed. Please discuss this with your cardiologist.
  • There is a chance that your baby may be smaller in size and weight. For this reason you will have additional ultrasound scans of your baby (at 28 to 32 weeks and 36 weeks gestation).
  • When your baby is born the medical teams will check their heart rate and blood sugar levels and perform an ECG (heart trace) at birth and after 3 weeks.

Other medicines

Some medicines can harm your baby during different stages of your pregnancy, delivery, and after you have given birth (postpartum) but many are considered safe.

Talk to your doctor or nurse if you have any questions or concerns.

Labour and delivery

Most women with LQTS can give birth in their local hospital with the correct precautions.

The team looking after you during delivery of your baby will avoid medicines and anaesthetics known to cause QT prolongation. The list can be found on the CredibleMeds website and includes high-dose oxytocin.

Your blood volume and electrolyte will be monitored closely and may need to be replaced.

ECGs will be done to monitor your QT interval. You will have a cardiac monitor when you are giving birth.

Your medical team will refer you to the cardio-obstetrics clinic if:

  • your QT interval is very prolonged (QTc is more 500ms)
  • you have an implantable cardioverter defibrillator (ICD)
  • you have had previous heart rhythm abnormalities 

After giving birth (postpartum)

If you have been prescribed a beta blocker to reduce your risk of serious heart rhythm abnormalities, it is very important that you continue to take this after you have given birth. This is because certain factors, such as tiredness and sleep deprivation can increase the chance of LQTS complications.

  • If your beta blocker dose was changed during your pregnancy it may need to be changed again after birth when your blood volume decreases. Please discuss this with your cardiologist.
  • Beta blockers are safe to take when breastfeeding.
  • If the genetic cause of your LQTS is known we may take blood from your baby to test for the faulty gene.

Resource number 5356/VER1
Published date May 2023
Review date May 2026

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