When does the second stage of labor conclude?

The correct answer is that the second stage of labor concludes when the newborn is fully delivered. This stage is characterized by the mother's active efforts to push the baby out through the birth canal. Once the baby is born, the challenges and efforts of this stage are considered complete.

The other options focus on different aspects of labor. The cervix being fully dilated pertains to the first stage, which is critical for the progression into the second stage. The delivery of the placenta occurs during the third stage of labor, marking the final phase after the baby has been born. Lastly, while contractions may subside or change after the baby is pushed out, they are not a determining factor for the conclusion of the second stage; rather, it is the successful birth of the newborn that marks its end.