What Happens After a Blood Test?

Rhesus factor

Some women are described as having Rhesus negative blood. This can be a problem if the baby has Rhesus positive blood. During delivery, blood cells from the baby can pass into the mother’s bloodstream and the mother reacts to the foreign blood cells by manufacturing antibodies to destroy them. If the mother becomes pregnant again with a Rhesus positive baby, these antibodies will pass to the baby and start to destroy his red blood cells.

So after giving birth, every Rhesus negative mother is given an injection of anti-D. This masks any of the baby’s red blood cells which have got into her bloodstream, so that the mother does not manufacture antibodies against them.

Women who are Rhesus negative have their blood tested repeatedly during pregnancy to make sure that they are not forming anti