Does anyone have any advice on what size is best?? One website I looked at says the 55" ball is too small and a 65" ball is best for women of my height (5ft 3") but then another site says 55" is best!!!
Does it really make that much of a difference??
The main thing is that your hips/pelvis are higher than your knees. This position is what helps get your baby into the right position for the birth. I am 5'7 and initially I got the 55cm one (the girl in the shop said it would be fine) but it was way too small. I now have the 65cm and it's fine. I'd probably like it to be even a bit bigger but I'm pretty sure it's fine. If I was your height I would probably still go for the 65cm one to be honest as I assume you are buying it for pregnancy reasons and not for actual exercise. Maybe see can you try one out in a sports shop if you are unsure.
You're best off going for the 65cm at least. You want your knees to be below your hips ;) You will lose a bit of height too w=once it's pumped an you're sitting on it.