Which gestation range applies to rats?

Which gestation range applies to rats?

• A. 19 - 21 days
• B. 21 - 23 days
• C. 24 - 26 days
• D. 15 days

Answer: (B)

Rat gestation lasts about three weeks, with most pregnancies delivering around 21 to 23 days after mating. This window reflects the typical development timeline for rats in standard laboratory conditions. A shorter range like 19–21 days aligns more with mice; a longer range such as 24–26 days is outside the normal rat gestation and not the standard expectation; 15 days is far too short for rat fetal development. Therefore, the 21–23 day span best matches rat gestation.

Rat gestation lasts about three weeks, with most pregnancies delivering around 21 to 23 days after mating. This window reflects the typical development timeline for rats in standard laboratory conditions. A shorter range like 19–21 days aligns more with mice; a longer range such as 24–26 days is outside the normal rat gestation and not the standard expectation; 15 days is far too short for rat fetal development. Therefore, the 21–23 day span best matches rat gestation.