Pregnancy Weeks 26-28 – Rho-Gam Administration

Rho-Gam is administered between Weeks 26-28 for mothers whose blood type is

Each person’s blood is one of four major types: A, B, AB, or O. Blood types are determined by the types of antigens on the blood cells. Antigens are proteins on the surface of blood cells that can cause a response from the immune system. The Rh factor is a type of protein on the surface of red blood cells. Most people who have the Rh factor are Rh-positive. Those who do not have the Rh factor are Rh-negative.

As part of your prenatal care, you will have blood tests to find out your blood type. If your blood lacks the Rh antigen, it is called Rh-negative. If it has the antigen, it is called Rh-positive.

When the mother is Rh-negative and the father is Rh-positive, the fetus can inherit the Rh factor from the father. This makes the fetus Rh-positive too. Problems can arise when the fetus’s blood has the Rh factor and the mother’s blood does not.