We recommend that you not do this and instead, wait for them to inform you. With few exceptions, employers may not inquire about an employee’s medical information unless the employee has requested an accommodation or leave, and employees are usually under no obligation to inform their employer of a pregnancy. The only exception is that some leave laws require advance notice if an employee is planning to take foreseeable leave (such as baby bonding).
Employers often want to ask this question because they believe they need to take special precautions with pregnant employees, but that is generally not the case. Click here to see additional things you should keep in mind.