There are SO many theories about dreams and going through psychological training you develop your own theory. If you are interested in dream interpretation here is a good link to what some say certain dreams mean:
http://www.dreammoods.com/
As for my personal belief from my studies and philosophy, when you dream in REM sleep your neurons are firing at random which neurological studies know to be true. Directly behind your forehead you have a part of your brain called the forebrain which was the last part of your brain to evolve which is responsible for executive functions like controlling emotions, etc that separates us from other species.
This forebrain is responsible for taking random signals that occur during REM sleep and interpreting them into something that makes sense. So for example lets say that the forebrain gets an image of a pirate, the feeling of falling and the smell of pizza. Your forebrain will interpret this into a story or dream and since while you are in REM sleep, your brain waves mimic your brain waves while awake, you can often recall these made up memories for a short time (since they are only stored in Short Term Memory.
So what's the fun in that? Well dreams can still be good tools of self-evaluation. You may have been shaken by this dream because maybe secretly you have been thinking of having a baby, or your body has signs of being pregnant. My suggestion is to keep a dream journal and see if you can see any patterns and who knows, maybe the future will tell you why this dream effected you emotionally so much!







