There may be a risk that vaccination itself can cause damage to an early foetus. It is sometimes carried by cats, dogs and sheep who pass the parasites that cause the infection in their motions. If you have a cat which uses a litter tray, it's sensible not to handle or change soiled cat litter in pregnancy unless you use rubber gloves and wash thoroughly afterwards. No matter how clean and healthy your pet is, wash your hands after handling it and before preparing food. The standard answer is to keep trying, without any contraception for a year.
Fertility is a matter of chance, like rolling the dice.
You may be lucky first time, but there is no guarantee you will succeed even after lots of attempts. For a list of other articles written exclusively for BBC Health visit our Features' Index page. The BBC is not liable for the contents of any external internet sites listed, nor does it endorse any commercial product or service mentioned or advised on any of the sites. Always consult your own GP if you're in any way concerned about your health.