Midwifery led unit - too high BMI

Hi

I've been told that I cannot give birth in a midwifery led until as my BMI is too high. I am only 25 weeks, but so far my pregnancy has been straightforward, my blood pressure is ideal and I have no problems. 

Is there a way that I can challenge this decision as it really does mean a lot to me to be there rather than in hospital? the only thing 'wrong' with me is that my BMI will be over 35 when I give birth.

Thanks x