Sorry Mrs P I must have replied at the same time as you!

To be honest if it was me I wouldn't do it. I get massages about once a fortnight as well as see a chirpractor and both of them have said they wont touch me with a 10ft pole in the first trimester. I think you should def call ahead and explain your situation to them, to be honest if they are quite a big day spa then they probably have a rule about pregnant women etc. I would just say to them that you are currently undergoing IVF and that there is a possibility that you could be pregnant but you dont want anyone to know. If it was me then I would swap the massage for something else, but you do what you feel is best xxx