Positive indirect coomb's test means you are already sensitized and antibodies
against Rh +ve blood are circulating in your blood. Theses antibodies may pass through the placenta and travel to your baby in the uterus
. If this baby is Rh +ve, then these antibodies will kill the red cells of your baby.
Depending upon the number of antibodies in your blood (antibody titre) the destruction of the red cells of baby takes place. This being the second pregnancy
, baby may suffer from severe jaundice
after the birth requiring exchange of the blood by Rh - ve blood. So you may have to keep Rh -ve blood donor ready at the time of your delivery. Also baby may require blue light therapy
depending upon the severity of the jaundice.
In subsequent pregnancies, the amount of blood destruction goes on increasing due to increasing titre of the antibodies, affecting the baby within the uterus. The baby may succumb within the uterus if left untreated.
The exchange of baby's blood can be performed while the baby is in the uterus.
Your Obstetrician will assess the antibody titre and will advice you accordingly.
I hope the situation is quite clear to you now.