Oils that should be avoided during pregnancy:
It may seem funny that things like clove, nutmeg and cinnamon are on this list, but in actuality nutmeg is very potent and when large amounts are ingested can cause nausea. Oils are very concentrated. In fact, cinnamon oil is so potent that many people opt to use a cinnamon stick instead of the oil.
Oils that are safe for use in pregnancy:
Like everything though, use in moderation. Remember, each individual can react differently to each oil depending on any existing medical conditions so seeking a physicians advise is recommended! I also recommend reading the original article for its additional precautions.
The original article can be found on Suite101