Morning sickness and oils

Jamie
I have horrible morning sickness. I have been dabbling with essential oils for awhile now and have read that peppermint can help with Nauseaus and headaches. 
Does any one know of using oils would be safe during pregnancy? I am so desperate to try something to help with the nausea but don't want to harm my baby. 
I use real mild blends that are safe for toddlers on my little one when he starts to get a cold and it clears up real quick. 
Any advice would be appreciated. Thanks!
Ti