Milky Mama, no carrier oils are not essential oils. (Don't worry, I'm a certified aromatherapist.) Most carrier oils are considered safe, though you should always watch yourself for allergic reactions. Also to consider, if you have a family history of nut allergy, you may want to hold off on using any nut based oil during pregnancy.
A carrier oil is any oil used to dilute and essentially, "carry" the essential oil. Since, EOs are the very very very distilled oil of a plant, they can be potent and often times are not safe to apply directly to the skin. So, you must dilute the EO in something. There are many ways to do this - through a nebulizer where it can be transmitted via airborne mist, or water, where it can be diluted and absorbed via the skin or inhaled. The last way, is through a carrier oil. You can use any oil for this, depending on where it is going to be applied and what you are going to use the oil/EO application for: (ie, burning with a candle and releasing an air mist, applying to the face, or another part of the body)
Generally, there are not very many EO's that are considered safe for use during pregnancy. That being said, I have worked through all three of my own pregnancies using a variety of EO's and been completely fine. (though there are certain ones I would not use under any circumstances). In addition, I know many practicing, well respected midwives, massage therapists and aromatherapists who use a variety of essential oils to treat quite a few condition of preggos and it's very safe. However, these people have extra training to do so.
All that being said, I really think Rose Hip Oil is safe to use as a carrier oil. I looked it up and it is made from the seeds of the plant, meaning that is a true, cold pressed oil and NOT an essential oil. I didn't think it was, but wanted to clear that up for people. It is very high in Alpha Linoleic Acid as well as Omega 3's and is commonly used to treat pigmentation caused by pregnancy as well as a variety of other hormonally based skin issues.
So....that being said, I think it's ok.
Use with caution and watch for any sign of sensitization.
As an aside, here is a list of safe and nonsafe essential oils for pregnancy:Safe anytime (including first trimester)
(use diluted and don't go in sun after applying, can cause photosensitivity)Safe after 1st Trimestar
(use with caution and stop use immediatly with any strange symptoms or sign of sensitivity!!!) Always use a carrier oil!
*Jasmine may be used during labor to relieve anxiety.
Remember, these are not the same as the herbal concentrations. Many of them are safe in that form. For instance, it's fine to have a glass of peppermint tea, or have nutmeg in your pie.
If you are ever in doubt, it is best not to use the EO until you can gain advice from a trained professional.