In March, the U.S. FDA reported a major shortage of Rhogam, the anti-D immune globulin most widely used to prevent Rh factor incompatibility in pregnancy. Without treatment, second and subsequent pregnancies can be endangered by antibodies created by the mother. With the shortage, the standard treatment of two shots for all pregnant females with Rh-negative blood can be challenging, but Billiontoone Inc.’s Unity prenatal test can eliminate the need for the immune globulin treatment in 40% of these pregnancies.