Stage 1 of labor is defined as:

• A. Stage 1 = onset of contractions to full dilation
• B. Stage 2 = full dilation to expulsion
• C. Stage 3 = expulsion to delivery of placenta
• D. Stage 4 = immediate postpartum stabilization

Answer: (A)

Stage one is the phase from the start of regular contractions with cervical changes up to the cervix being fully dilated to about 10 centimeters. This period includes the early latent phase and the more rapid active dilation, all aiming to open the cervix enough for the baby to pass through. Once the cervix is fully dilated, labor moves into the next phase, from full dilation to the baby’s delivery. The following stage involves delivery of the placenta, and the final stage focuses on the immediate postpartum stabilization of the mother and newborn.