Abnormal stage of labor的用法和样例：
- The second stage of labor usually lasts 4 hours.
- The first stage of labor usually lasts ca. 2 hours.
- You are now in the preliminary stage of labor.
- The amniotic sac breaks and is expelled in the third stage of labor.
- This stage of labor is followed by actual abdominal straining and production of the puppies and placentas.