Facts and Numbers

Risks to patients with congenital heart defects during pregnancy

The following conditions present a serious risk to patients with congenital heart defects during pregnancy:

  • Myocardial insufficiency (weakness of the heart muscle)
  • Cardiac dysrhythmias
  • Syncope (sudden loss of consciousness)
  • Endocarditis (inflammation of the heart valves)
  • Development of thromboses and embolisms
  • Brain abscesses
  • Increased risk of cyanosis
  • Tearing of the main artery
  • Tearing of already dilated parts of the main cardiac or cerebral arteries
  • Sudden cardiac death

Typical dangers for the unborn child are:

  • Miscarriage
  • Premature birth
  • Abnormally low birth weight


For most young women with heart disease, their condition does not affect their choice of contraception. If no ideal method of contraception is available, the least unfavourable option should be selected. For some heart patients, becoming pregnant can pose a much greater risk than the risks posed by some contraceptives.

Gynaecologist’s considerationsCardiologist’s considerations
Conventional birth-control pills
  • 5% increase in blood pressure
  • Risk of blood clots is increased 2–4 times
  • For smokers aged 35 years plus there is an increased risk of cardiovascular disease
‘Mini-pills’ (low-dose gestagen), contraceptive injections, 
contraceptive implants (both gestagen)

  • Poor compliance produces a lower protective effect
  • Do not affect blood pressure
  • Thrombosis risk
  • Effect on metabolic status
  • Bleeding disorders
  • Appetite/weight problems
  • Mood swings
  • Poor compliance
Coil intrauterine device with or without hormones
  • Low risk of general side-effects
  • Possible risk of infection
  • Heavy bleeding (without hormones)
  • High endocarditis risk
  • Multiple partners
  • Increased bleeding problems with warfarin therapy and cyanotic drugs
Morning-after pills (gestagen)
  • Pregnancy risk of 0.5 – 3%
  • Pregnancy is a major medical risk
Barrier methods
  • Low pretection
  • Pregnancy is a major medical risk

Reference: Chief Physician Ulf Thilén, presentation at Paediatric Cardiology Conference, Västerås, 2005