Equally spread across all of the blood groups, 15% of each blood group is Rh negative. 85% are Rh positive. If the pregnant mom is Rh negative and the baby is Rh positive, the mom has to have a couple of shots so she can't build up immunities to future RH positvie babies. The shots are no big deal at all and every mom is routinely checked nowadays. I wouldn't refuse a donor just because she's positive unless you and your husband both are negative and you're no-tell. Best of luck!