I bought these SRC Pregnancy Shorts when I was in Australia and had just found out I was pregnant. Unfortunately due to complications I was essentially bed-ridden for the duration of my pregnancy and only used these brilliant support shorts once or twice at most. (obviously worn like exercise/bike shorts OVER underwear!)
I'm tall and was worried about my back and pelvis support which is why I originally bought these. They are very popular in Australia, please check out the website for yourself, but basically they support your 'baby carrying' pelvis to reduce stress placed on it and be in the best shape for delivery.
I thoroughly looked into this before buying them and got feedback from our Consultant, and I would recommend them for sure. They are very well medically researched and are not a fad product, they have a range of similar support items for pregnancy/pregnancy recovery/post general surgery etc.
Please check the site to check your size, these are a MEDIUM.
Price in Australia is AUD$189 (£108) but am selling these virtually brand new for £40.