Been pregnant 3 times and each time suddenly couldn't face my beloved freshly ground coffee and felt violently ill when serving Felix to the cat. First time around my instinct told me this might be it, positive test soon followed. Second and third times I remembered previous experiences and just knew, but obviously tested to confirm...
Each time my sense of smell has been incredibly heightened to a very inconvenient degree, interestingly it is a very ingrained natural response to keep pregnant women eating bland, and therefore "safer" foods. The body's own response to keep you away from rotten and poisonous foods.
After birth, reverts immediately and have always been desperate for a decent coffee...
HTH...good luck