In Canada YYZ-YYC I heard a call for a doctor, we taxied to the gate and were met by paramedics who were waiting at the gate.
For most medical conditions, the gate is most practical as elevators are available to take a patient on a gurney to where the ambulance is parked and you don't have to navigate an unfamiliar crew about the apron.
In the tragic case of the 6 month pregnant mother with sudden pain, time and minimal disturbance to the patient is vital. The best tactic would be to use a catering truck to wheel out the patient to the deck and lower her to the ambulance.
Obviously the airport and ambulance need to have a agreed plan and route that all local ambulance crews are familiarised with and a gurney that fits in the aisle must be available.
The airport fire station would be a good place for this, especially as the crews could be trained to safely get the patient to the ambulance and nobody has to worry about gate navigation.