Had a miscarriage, my husband is rh negative blood type, could that be a reason why? the doctors told him he is a rare blood type, can i get pregnant?

Not the problem: I'm sorry for the loss of your unborn child. One man in around six in the us is rh negative and this wasn't the cause; there can be problems if he is positive and you are negative especially if there's noncompliance but you'd have been told about this. "rare blood type" may be hyperbole; there are hundreds of subtypes of blood & if you can find his variant we can help you find resources.