Which stage of labor is defined by contractions that cause cervical dilation?

• A. Stage one
• B. Stage two
• C. Stage three
• D. Stage four

Answer: (A)

The initial stage of labor is defined by contractions that progressively dilate the cervix from closed to about 10 centimeters, allowing the baby to move into the birth canal. This stage is often described in two phases: a beginning phase with milder, irregular contractions that start the dilation, and a later phase with stronger, more regular contractions that accelerate cervical opening. The key feature here is cervical dilation driven by uterine contractions, which sets up the conditions for the baby to be delivered in the next stage. After dilation reaches full, the next stage involves the delivery of the baby, followed by placental separation and postpartum stabilization in subsequent stages.