Yeah I've heard the same thing. Don't have it up too high and make sure it is turned off once you get in. I think that it is up too high it is the same as having a really hot bath or doing too much exercise, you body gets overheated and your risk of m/c increases.

With TTC I think the only affect it might have is that if your DP/DH gets too hot "down there" it can lower his sperm count and increase your chances of concieving a girl (boy sperm tend to die off in the heat).

Jorja