Parents' rh factor may complicate pregnancies

Parents' rh factor may complicate pregnancies

BENGALURU: The anticipation of welcoming a newborn brings joy not just for the parents but also the whole family. It is a time for nurturing, caring and taking the necessary precautions, so that there are no complications threatening the baby or the mother at the time of birth.

Expectant women who have the blood group Rh (Rhesus) negative, which means they may be either A negative or B negative and whose husbands’ have a positive blood group, need to be extra careful. Babies of such parents are at the risk of some severe complications if the baby also has positive blood group. If their blood comes in contact with the mother’s blood in the womb, they can suffer severe anaemia or jaundice. Timely management to prevent such life-threatening problem, through the right care and treatment can save the newborn’s life.  

Decoding the RH factor in Pregnancy

The Rh factor is a type of protein on the surface of red blood cells. Those individuals who have the protein are Rh-positive. Those who lack the Rh factor are Rh-negative. When the expectant mother’s blood group is Rhesus negative and the husband’s is Rh positive, the baby’s blood group could be either negative or positive. If the factor is same as the mother’s then there would not be a problem. If the baby is Rh positive, then there is risk of complications.

When such a situation arises at the time of the first pregnancy, it can be prevented by sensitising the woman by giving an injection. Isoimmunisation, also known as ‘sensitisation,’ refers to the development of antibodies to Rh-antigens. When women who are Rh-negative are exposed to a source of Rh-positive blood with the Rh-antigens on their surface, they are therefore, ‘foreign’ to the woman’s immune system. These antibodies do not affect the woman but may cross the placenta and affect the baby through its blood.

The danger does not end there. In the subsequent pregnancy, if the blood types of the mother and baby are again incompatible, the mother, who is already sensitised, produces antibodies which can enter the baby’s blood and destroy the baby’s red blood cells. This is Hemolytic disease of the fetus and the newborn (HDFN), a blood disorder that causes severe anaemia and jaundice. If left untreated, it can result in stillbirth or severe brain damage in the newborn.

In order to assess if the expectant mother is sensitized or not, every Rh negative pregnant woman is tested with Indirect Coombs test (ICT). If ICT is negative, Anti D injection is given to her at around 28 weeks of pregnancy to prevent sensitisation. If ICT is positive, the antibody titer is checked for. Antibody titer is a laboratory test that measures the level of antibodies in a blood sample. The antibody level in the blood reveals whether or not the mother has been exposed to an antigen or something that the body thinks is foreign.

- Dr Anita K Mohan, Consultant Obstetrics & Gynaecologist, Fortis Hospital

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