Yes, this difference can affect your pregnancy. Since you are Rh-negative (B-) and your husband is Rh-positive, your baby may inherit his Rh-positive status. If your blood mixes, your immune system could produce antibodies against the baby's blood (Rh incompatibility). To prevent complications, you will need an injection of Rho(D) immune globulin (commonly known as RhoGAM or Anti-D). This is typically administered around the 28th week of pregnancy, and again within 72 hours after birth if your baby is confirmed to be Rh-positive. It is safe and highly effective. Please consult your obstetrician to schedule this.