Have you been having regular periods? Why do you suspect that you may be pregnant?
If in doubt of pregnancy
- you should get pregnancy testing kit/see your doctor and he can get urine or blood testing done for pregnancy.
If both parents have negative Rh type blood (with confirmed/written report), then as per the the pattern of inheritance, the baby's blood group
has to be negative. IF there is any discrepancy, the blood group of baby and parents should ideally be rechecked.
I hope I've been able to clear your doubts.