Because pregnant women with Rh-negative blood are at risk of developing Rh (D) antibodies, they are given Rh (D) immune globulin 300 mcg IM in any of the following situations: After any significant vaginal bleeding or other sign of placental hemorrhage or placental abruption After a spontaneous or therapeutic abortion After amniocentesis or chorionic villus sampling Prophylactically at 28 weeks If the neonate has Rh (D) - positive blood, after delivery Modifiable risk factors Pregnant women should not use alcohol and tobacco and should avoid exposure to secondhand smoke.