Jean, IIRC about the same. Here's a link to the Experts talking about it: http://www.preeclampsia.org/forum/viewt ... f=19&t=331
Sugabbz, since you developed HELLP in your third pregnancy, you're a bit of a rare bird. It's unusual to develop these conditions for the first time in a third pregnancy. However, you have company here. We have a number of posters who have developed it in a pregnancy that was not their first.
Since you're not someone who got it in a first pregnancy, the statistics I'm citing just don't apply to you. It's too rare for studies to have been done and too hard to find a research population!
In your shoes I would want to consult with a maternal-fetal medicine specialist who researches these sorts of pregnancies. Here's a link to help you find one in your area: http://www.smfm.org
(search by state, because their search engine is a bit weird and sometimes excludes people who are close to me if I search by city.)