Engagement in labor refers to which description?

• A. It occurs when the cervix is fully dilated
• B. It occurs when the presenting part lies at the pelvic inlet
• C. It occurs when the presenting part passes through the cervical canal
• D. It occurs when the presenting part is at the level of the ischial spines

Answer: (D)

Engagement is when the presenting part has descended into the true pelvis to the level of the ischial spines, i.e., it is at zero station. This moment marks that the widest diameter of the presenting part has passed through the pelvic inlet and is beginning to descend within the pelvis. It is a milestone that indicates the baby is entering the pelvic cavity and ready to begin active descent with contractions.

The other descriptions don’t fit engagement: fully dilated cervix refers to dilation of the cervix, which occurs later in labor; the presenting part passing through the cervical canal describes descent during dilation, not the point at which it reaches the pelvic inlet level; and being at the pelvic inlet describes entry into the pelvis but before reaching the level of the ischial spines (not yet engagement).