A 30-year-old woman, gravida 2, para 0, aborta 1, at 28-weeks' gestation comes to the office for a prenatal visit. She has had one previous pregnancy resulting in a spontaneous abortion at 12…

A 30-year-old woman, gravida 2, para 0, aborta 1, at 28-weeks' gestation comes to the office for a prenatal visit. She has had one previous pregnancy resulting in a spontaneous abortion at 12- weeks' gestation. Today, her vital signs are within normal limits. Physical examination shows a uterus consistent in size with a 28- week gestation. Fetal ultrasonography shows a male fetus with no abnormalities. Her blood group is O, Rh-negative. The father's blood group is B, Rh- positive. The physician recommends administration of Rho (D) immune globulin to the patient. This treatment is most likely to prevent which of the following in this mother?