rhesus negative 
(abbreviation Rh-negative)
adjective Medicine
Lacking the rhesus factor.If a baby is rhesus positive but the mother is rhesus negative, then the mother could become sensitive to the baby's blood....
- Blood group women who have a rhesus negative blood group may need to have an injection to prevent problems for subsequent pregnancies.
- But if the mother is rhesus negative and the father is rhesus positive, it could lead to problems if the baby is also rhesus positive.