First delivery would be safe.... but subsequent delivery with the same given case can be fatal to the developing foetus.... and this condition would be called as Erythroblastosis fetalis...
Now what happens in this...!
First you need to know that Rh -ve means complete absence of Rh factor/antigen in blood... and Rh +ve means presence of Rh factor in blood.... and also u need to know that when Rh -ve blood is transfused in Rh +ve person no harm will be caused BUT... But if Rh +ve blood is transfused in Rh-ve person he will start developing antibodies against Rh +ve antigen
Now See when rh -ve mother is first time pregnant with the rh +ve child in her womb.... then baby will develop without any difficulty since Rh antigens of the foetus do not get exposed to
the Rh-ve blood of the mother in the first pregnancy as the two bloods are
well separated by the placenta. However, during the delivery of the first
child, there is a possibility of exposure of the maternal blood to small
amounts of the Rh+ve blood from the foetus. In such cases, the mother
starts preparing antibodies against Rh antigen in her blood. In case of
her subsequent pregnancies, the Rh antibodies from the mother (Rh-ve)
can leak into the blood of the foetus (Rh+ve) and destroy the foetal RBCs.
This could be fatal to the foetus or could cause severe anaemia and
jaundice to the baby. This condition is called erythroblastosis foetalis.
This can be avoided by administering anti-Rh antibodies to the mother immediately after the delivery of the first child