If you are having an IVF cycle, yes, but generally as you get closer to the egg collection there may be some discomfort and abstinence for 2-3 days prior to the egg collection is desirable to improve the quality of the sperm.
After the egg collection you are generally advised to abstain if you had more than 15 eggs collected as the ovaries are very fragile.
After the embryo transfer resumption of sexual intercourse improves the chance of the treatment cycle being successful and is generally advised.
If you are having a frozen embryo transferred in a natural cycle in which you ovulate and you have a chance of natural conception (e.g. open Fallopian tubes and sperm are present) there is a risk of multiple pregnancy (if spontaneous conception occurs and the transferred embryo implants). Ask your doctor about your unique situation for advice. If ovulation is suppressed – such as with a cycle when you take hormones sexual intercourse is safe. As with IVF cycles sexual intercourse is advised after the embryo transfer.