Apart from inheriting blood groups from parents (A, B, AB, and O) the unborn child also inherits another factor known as the Rh factor.
So, what is this Rh factor all about?
Rh (Rhesus) factor is a protein seen on the surface of a person’s RBC’s (red blood cells). If it is present in the person’s blood cells (RBC’s), such a person is known as Rh positive(D+/Rh+), and if is absent Rh negative(D-/Rh-). Most commonly seen is the Rh positive accounting for 80-85% of the population.
What is Rh-Incompatibility?
If you and your partner (mother & father) are either Rh+ or Rh – or if the mother is Rh + and the father is Rh-, then there is no issue and it poses no threat to your unborn child. The problem arises when the father is Rh+ and the mother is Rh-, this can lead to Rh incompatibility or Rh disease in the child.
To summarize it:
- Rh + mother & Rh + father = Rh +/- baby (no sensitization)
- Rh – mother & Rh – father = Rh – baby (no sensitization)
- Rh + mother & Rh – father = Rh +/- baby (no sensitization)
- Rh – mother & Rh + father = Rh +/-baby, if Rh- baby (no sensitization) & if Rh + baby (sensitization or Rh incompatibility)
How can it affect your pregnancy?
Initially when the Rh – mother is carrying an Rh + baby, on delivery the baby’s blood gets into the mother’s circulation. This doesn’t affect the newborn, but the subsequent child (2nd or 3rd) may develop various hemolytic diseases.
This is because the Rh – ve mother after her first delivery develops anti-Rh or anti-D antibodies and these attack the foreign D+/Rh + (antigen) on the RBC’s of the next baby.
It is important to note that most often during the delivery of the first child, the Rh+ baby’s blood gets mixed in the mother’s circulation. But sometimes, it can happen earlier when the baby is in the womb in cases like:
- bleeding caused by an injury/accident
- post amniocentesis
- post-CVS investigation
- ectopic pregnancy
This leads to an immune reaction (antigen-antibody reaction) in the mother. In cases of miscarriage and induced abortion, the first child may be affected if the mother gets previously sensitized.
Continue reading @Rh Incompatibility — how it affects your pregnancy Part II