Final answer:
The nurse can determine that the client is in the 2nd stage of labor when the cervix is dilated completely to about 10 cm, allowing for the expulsion of the baby.
Step-by-step explanation:
A nurse can determine that the client is beginning in the 2nd stage of labor when the cervix is dilated completely, which typically is about 10 cm.
This dilation indicates that the first stage, which involves the thinning and dilation of the cervix, has been completed, and it is now time for the baby to be expelled from the uterus.
This second stage of labor involves the contractions of the uterus and the mother pushing with her abdominal muscles to assist the delivery.
Finally, the third stage of labor is the passage of the placenta after the newborn has been delivered.