There are many warnings about using essential oils when you are pregnant. I know of one thing for sure: You can muscle test any essential oil (eo). To save yourself time, avoid any eo's that from grocery and health food stores. Go further to the source. I use, and have been very satisfied with Young Living eos. They have a seed to seal guarantee. Which means no GMOs, no pesticides and herbicides, and most importantly no shortcuts in the distillation process. YL has farms all over the world to grow the herbs. If an essential oil they sell was not distilled and grown on one of their farms, YL provides the information so the public knows where they are getting the oils.
Now to the good stuff, What to use for what. All of the recommendations are for Young Living oils.
Nausea: Peppermint, Lemon, or Di-Gize
Heartburn: Peppermint, Di-Gize
Sleeplessness: Peace and Calming, Lavender, or Valor
Stretchmarks: Lavender and/or Gentle Baby
*All of these oils can be used topically, internally, and diffused. Take your pick :)
Please email me or leave a comment if you have specific questions. There is no reason to feel helpless or uncomfortable if it can be prevented. My email is firstname.lastname@example.org. Also, I would highly recommend the book, Gentle Babies by Debra Raybern. This book has plenty of information to help you- including but not limited to: pregnancy, childbirth, and after care. Debra is a Young Living distributor and all suggested products with the exception of a small handful are Young Living.