That sounds like a conflict with RH factor's. If the woman is RH- (negative) & the man is RH+ (positive) then the baby will (generally) have the dad's RH+ & the woman's body will think its something to fight & kill, hence the miscarriages. If the woman gets a shot & i just went blank on what its called, but it helps to prevent the woman's body from rejecting the foreign object (baby). I am also RH-negative and A-. My husband is RH+ & i forget the blood type, but its positive. after all 4 of our kids I had to get a shot so i didn't miscarrying. RH- is rare On 4/4/2016 6:25 PM, Adiene Humble via wrote: > I have a strange question. My mom and her sister had negative blood which as we know is rarer than positive and I’ve wondered if this factors comes from a particular nationality or is it something that is just worldwide? This negative issue applies difficulties in many ways with childbirth. My aunt lost two boys before she had her two girls and then no more children. My mom had trouble having me and our family line have twins, lots of them. This has got to be a genetic connection. > >