I use the peppermint one and I think it's fine. It was my fiances mom that gave it too me and she's a nurse so I would think she would know if it's not safe.
I use essential oils all the time? Why do you think their not safe?
I read that cinnamon based oils aren't safe in first trimester. In fact, a lot aren't. I'm an avid user of oils. I want to be able to use thieves. I ordered the Gentle Baby book, so I hope it helps.
Some oils are unsafe for pregnancy. My mother had gotten me a headache relief oil roller and it turns out one of the oils in it isn't safe for pregnancy. Just look up an oil before you use it
We are big time users & my husband's step mom has done a lot of research into this-because our hormones are so different from usual while pregnant when topically applied we are more prone to reactions such as rashes & burning. There's no evidence linked to miscarriage or defects just our own skin irritation.