B'sha'ah tovah!
Relations are fully permitted throughout pregnancy.
Mitzvat onah – the husband's obligation to his wife to have relations at regular intervals is not waived during pregnancy unless she agrees.
There is a Talmudic statement to the effect that relations in the first trimester are difficult for mother and baby. It is not clear what is meant by this statement, except that the statement does
not have halachic force. If there is no medical contraindication (and generally, there is not) and if the woman desires relations, they are fully permissible during the first trimester.