Hi Luey

Aromatherapy involves the use of essential oils in different ways, e.g. massage, bath, inhalation, so genuine aromatherapy and essential oils are one-and-the-same thing.

During pregnancy, you should avoid:
Aniseed, sweet fennel - these have oestrogen-influencing properties
Clary sage, sweet marjoram, cedarwood, cypress, peppermint, rosemary, jasmine and rose - some of these have emmengogue-type actions or are uterine tonics, meaning that they can encourage menstrual bleeding and/or uterine contractions.

There are some others that aren't safe during pregnancy, such as pennyroyal, sassafras, wormwood, sage, mugwort, tansy, thuja and parsley seed ... but these are generally considered quite toxic, and aren't readily available anyway.

Some of the oils that aren't safe during pregnancy can be great to use during labour, such as clary sage, jasmine, peppermint, and rose (when you want your uterus to contract!).

There are lots and lots of the other essential oils that are very safe during pregnancy and can be very beneficial - I have been using spearmint, tangerine, sweet orange, mandarin, lavender and german chamomile all through my pregnancy, in my bath, on my pillow, or in a massage oil (which DH kindly obliges me with!).