Pregnancy is protected in Europe and it is unfair to dismiss staff because they are pregnant, whether or not it is still on probation period or not.

If your job no longer exists when you come back, perhaps because the project you were working on has come to an end, there is a redundancy situation. Even if you have not worked for your employer for long enough to qualify for a redundancy payment, you are afforded special protection as a woman on maternity leave.