A visibly pregnant woman goes into cardiac arrest. What would you do to minimise harm to the foetus?

1. Call for Emergency Medical Services: The first step is to call for emergency medical services immediately. Dial your country's emergency number and provide them with all the necessary information.

2. Start CPR: While waiting for medical professionals to arrive, start performing cardiopulmonary resuscitation (CPR). The American Heart Association recommends using a ratio of 30 compressions to 2 breaths.

3. Position Correctly: If possible, position the woman on her left side. This can help improve blood flow to the heart and the fetus by reducing the pressure of the uterus on the major blood vessels.

4. Use an AED: If an automated external defibrillator (AED) is available, use it. AEDs are safe to use on pregnant women and can significantly increase the chances of survival.

5. Continue CPR until help arrives: Continue performing CPR until medical professionals arrive. They will be able to provide advanced life support and take over the resuscitation efforts.

6. Transfer to Hospital: Once the medical team arrives, they will likely transport the woman to the hospital for further treatment. The hospital team will be able to provide specialized care for both the woman and the fetus.

Remember, the best way to minimize harm to the fetus is to restore blood flow to the mother as quickly as possible.