5 months is not very long. My company probation period is 6 months. Anyway, it does not matter that an employee is on probation, as long as the employee has worked for the employer for at least 90 days before the birth of the child and meets the other eligibility criteria for maternity leave under the Employment Act.
You should wait and see, ya. dont't be too rash. Unless your work is giving you too much stress and threathen your pregnancy.