Is it possible to become pregnant if your dhea level is high?

Yes. Elevated DHEA (dihydroepiadrosterone, a testosterone precursor) can lead to miscarriage and to prevention of ovulation. This is not something that occurs in every case, but these consequences can happen. If your DHEA is elevated discuss pregnancy with your ObGyn.
Yes. Dhea is a precursor for over 50 other hormones, including estrogen and testosterone. Rarely would it prevent pregnancy unless it leads to such high levels of estrogen or testosterone that you are not ovulating. Once you become pregnant, however, it can lead to preterm labor and delivery. I would control it before you attempt conception.