Air carrier pilot reported a conflict with a helicopter near the departure corridor of Runway 27 in BOS.

Narrative

As we took off from Runway 27 in BOS; soon after liftoff there was helicopter traffic over the river and just west of the departure runway that was too close to our departure corridor and altitude. While Tower pointed the traffic out and we visually acquired the traffic; I had to climb more than planned in order to ensure safe separation from the helicopter. Additionally; had we had an engine issue or failure that required us to fly our company engine out procedures; the helicopter would have been a direct conflict. I estimate based on visual and TCAS alerts that we climbed at least 700 feet above the helicopter; but that was after adjusting the normal planned climb power and profile to climb more than initially planned. We were unaware of the helicopter traffic until we were past our safe takeoff reject speed.Conduct a review of the BOS helicopter in departure corridor procedures and do not allow helicopters off the departure runway when aircraft are taking off. Alternatively; alert aircraft of conflict helicopter traffic before clearing the aircraft for takeoff giving the aircraft the opportunity to delay the takeoff until the helicopter is ensured to not be a conflict with the takeoff and climb-out.