Our Mk 1 Airbus, (A300), did this. I think it is to get the pressurisation system working before lift off so there isn't a sudden change in cabin pressure when airborne. After take off the system will control the cabin rate of climb to around 500fpm as the aircraft climbs at 2000 or 3000 fpm.
If you abandon take off the outflow valves will open to ensure there is no differential to prevent doors from being opened.
Hope this helps.