The second stage of labor begins at:

• A. Full dilation to birth
• B. Onset of pushing to birth
• C. 8 cm dilation to birth
• D. Transition period

Answer: (A)

Second stage begins when the cervix is fully dilated (10 cm) and ends with the birth of the baby. At this point the birth canal is wide enough for the presenting part to descend and be delivered, assisted by contractions and pushing. While some texts reference the onset of pushing, the standard boundary used in exams is full dilation to birth. The option suggesting 8 cm dilation is incorrect because the cervix must be completely dilated before the baby can be delivered. The transition period occurs toward the end of the first stage, not the second stage.