I had a friend whose wife used to have similar head spinning attacks during pregnancy.
She died during giving birth - the baby survived.
It turned out that she had a small leakage in some artery or cappillary in her brain ever since she was a child and she never knew and others too did not know... so something happened during pregnancy and she would always have head spinning and attacks. Then during her delivery the leak turned into a major brain hemorrage because of all the strain of pushing the baby out.
I wonder if gauri has some undiagnosed leak too. The head spinning seems a little odd.