Nicola Duffield (registered dietician) answers:
The mechanism by which your senses are changed during pregnancy is still poorly understood by science. However, we do know that your senses are heightened especially those of taste and smell. This may be due to the changes in hormones such as progesterone. These sensory changes are great contributors to the nausea and taste aversions associated with pregnancy and do abate once the baby is born if not before.
It is common for women to be nauseated by smells that they used to like such as their favourite perfume. I suggest avoiding all scented products especially in the first trimester and while the "morning sickness" phase is still around.
Sour foods in general seem to be better tolerated by anyone suffering from nausea. In order to keep that nausea at bay I would recommend frequent small meals and if you can't stomach a meal something like a home-made pineapple smoothie or having a glass of lemon water with a meal may help transition you through the "yucky" phase and into the "honeymoon" stage of pregnancy.
If you are battling to consume sufficient nutrients, I suggest that you consult with a registered dietician who will be able to advise you on foods that are palatable and meet your nutrition needs.