I remember how my body changed and reacted differently during pregnancy and some of it didn't change back!
I've always had flare ups but become far more sensitive during pregnancy, especially perfume related sensitivites.
I've stripped out all fragrances and mainly buy natural toiletries now.
If it's just soap you're after then silverfrog mentions Urtekram - they make a no perfume soap, it is excellent - cheap (£1.60ish I think), frothy, long lasting and allergy approved.
I've been using A'kin gentle unscented shampoo for a number of years as I discoverd Sodium Laureth Sulphate (in most shampoos) was giving an itchy scalp - but I only discovered it was that after stumbling upon sls-free shampoo!
Urtekram shampoo is ok but I never felt clean using it. The A'kin unscented shampoo is just gorgeous to use if you have a few more pennies - fab lather which is lacking in many sls-free products. Also won an award for eczema/allergy product last year.
If you do want to go down the fragrance-free route then you could try
www.eco-essentials.co.uk/index.php?cPath=32
for a very large selection of everything unperfumed, natural and sles free products which are great on sensitive allergy prone skins.
I hope you find something that doesn't cause your reactions...