Even though thrush is not a sexually transmitted infection it really is probably better to avoid sex until your thrush has cleared up. Vaginal sex may be uncomfortable and it could be that you can pass on thrush to your partner. However if your partner doesn't have any symptoms then you don't have for treatment.
Before taking any medication you should inform the doctor, nurse or pharmacist if you think you may be pregnant. If you are pregnant then you should utilize the cream and pessaries and not the oral tablets. Thrush is not harmful to you or the baby.