Vagina's are self cleaning. All you need to do is make sure you clean the area with some water - not douching though. Even just use a wet cloth and wipe the outside of your vagina. You don't want to mess up the natural bacteria that are down there or introduce other bacteria either.
Be careful when cleaning your vagina. Our vagina's have natural bacteria and if we disrupt it with douche's and soaps we can get yeast infections. Plus you are pregnant and are more vulnerable to yeast infections. Clean the outside of your vagina well (it is not a good idea to clean the inside.. for reasons I stated before) If your husband just ejaculated inside of you, then gently wash yourself in the shower, then take a nice warm bubble bath with scented bath beads...
Congrats on your pregnancy!
~VQ