Timing vaccinations with breeding can be tricky. The one vaccine you MAY not have any choice on is the Rabies vaccine. In USA it is legally required giving no medical flexibility on timing of administration. If Rabies is legally required then it MUST be given in accordance with the law. The other vaccinations have more flexibility in timing of administration. Determining the medical pros vs cons of the unique situation is the best way to determine the appropriateness vaccine administration at that time.
In situations involving a breeding female, the concern with vaccination is two fold:
Vaccines work by stimulating the immune system like unto a disease just much less severe. Thus, general malaise (not feeling good), fever, loss of appetite, etc often accompany vaccinations. Having recently had a vaccine for tetanus myself I can readily attest to how badly one can feel after
a vaccination. ALL of these effects can disrupt the female reproductive cycle even “stall” it or shut it down. If administered close to mating (within 2 weeks) I would be very concerned that vaccinations will have a detrimental effect on the bitch getting pregnant.
Most vaccinations especially to diseases like parvo virus, canine distemper, etc are modified live viruses (MLV). MLV are live viruses that are weakened to the point they cannot infect healthy immune systems. BUT they are very dangerous to embryos and even to feti (later in gestation). They can infect these embryonic/fetal tissue and cause significant damage even loss of the pregnancy. If given close to mating (it takes a week or so for the virus to get out of the body) I would NOT risk vaccinations because of the potential harm to the developing puppies.
I will NOT personally or professionally vaccinate any bitch who is pregnant or will be bred in the next 10 days for anything but rabies and ONLY if that is legally needed. I really prefer to NOT do Rabies either but my hands are tied by the law. I recommend vaccine boosters for distemper/parvo/hepatitis about a month before potential breeding. This gives plenty of time for the effects of the vaccine and the virus from the vaccines to clear the body as well as plenty of time for good antibody formation. High levels of circulating antibodies will result in high levels in the colostrum (first milk) that the puppies get giving the puppies good immunity until their immune system develops.