Which essential oils should be avoided during pregnancy?

During pregnancy, certain essential oils are often recommended to be avoided as a precaution. These include basil, camphor, clary sage, hyssop, myrrh, peppermint, rosemary, sage, thyme, wintergreen, lemon, bergamot, ginger, and ylang-ylang. Because pregnancy is a sensitive time, extra care should be taken with essential oils, and diffusing gentle oils is generally considered a safer approach than internal use.