Ideally, a female should have completed all her boosters and vaccinations before she becomes pregnant. Her immunity to certain illnesses is of prime importance because she will be passing on this immunity to her offspring via her milk when newborn kittens start suckling. A cat that is fully vaccinated when bred has higher antibody levels which are beneficial for her kittens. Your veterinarian may choose to conduct a titer test to assess your pet’s antibody levels before deciding whether or not your cat needs to be vaccinated.
However, there are certain types of vaccines that cannot be given to pregnant cats. So if you are planning to have your cat mated, make sure that her vaccines are fully updated before you breed from her. Consult your pets’ health care.