Pregnancy and weight

So I've been ttc for 9 months and I think I may be lucks in for a positive. However it's come at a time where I was going to not try to hard to get pregnant. That's because I've given myself a reality check with my weight. I'm tall so I carry my weight ok (5ft10) But enough is enough. I'm too heavy. My health is ok but anymore weight and it won't be.

I need to lose 5 stone. I know how to do it not pregnant but Can I safely lose weight while pregnant? Or maintain?