In month 5, which development is described as occurring?

• A. The fetus loses circadian rhythms
• B. The fetus develops circadian rhythms
• C. The fetus stops moving
• D. The fetus stops hearing

Answer: (B)

In month five, the fetus begins to establish circadian rhythms, meaning it starts showing day-night patterns in activity and rest that align with the mother’s 24-hour cycle. This milestone happens as the nervous system and sensory systems mature enough to respond to light-dark cues; the retina detects light and sends signals to the brain to help organize sleep-wake cycles. Hearing is still developing, and the fetus continues to move, so the idea is not that movement or hearing stop. The key idea here is the emergence of these internal daily rhythms that begin to organize the fetus’s activity in sync with the external day-night cycle.