The fetus begins to respond to sound by the end of which trimester?

• A. First trimester
• B. Second trimester
• C. Third trimester
• D. Birth

Answer: (B)

Hearing development in the fetus reaches a functional point around mid-gestation. By about 24 weeks, which is late in the second trimester, the fetus begins to respond to sounds, showing reflex movements or startle responses and can hear maternal voice. By the end of the second trimester these responses are evident, and later in the third trimester they become more robust and discriminating. So the milestone “begins to respond to sound” aligns with the end of the second trimester.