Final answer:
The baby's hearing begins to develop around the 18th week of pregnancy and the structures responsible for hearing are well formed by the 25th week. Sensitivity to sound improves as the pregnancy progresses.
Step-by-step explanation:
As a nurse, you would inform your patient, Anna, that her baby's hearing begins to develop around the 18th week of pregnancy. By the 25th week, the structures of the inner ear responsible for hearing are well formed, and the baby can start responding to sound. It's important to note that at this stage, the baby's hearing is not fully matured, and sensitivity to sound will continue to improve as the pregnancy progresses.