Legally no, morally without question yes.
The first paragraph from the link snags posted states "No, you don't have to tell them anything. The fact that you are pregnant should not have any bearing on whether you are the right person for the job" to the question of telling a prospective employer about a pregnancy.
I entirely disagree with the second part - if an employer is interviewing for a position then it is clearly a position the employer wants to fill, and therefore being pregnant absolutely does have a bearing on whether a person is the right person for the job. If the person goes on Mat leave for a year a few months after joining, then the employer has a position where the employee employed for the position is not in a position to do their job.
May not be such an issue for a large company, but what about small companies?