What notice of her intention to take maternity leave is an employee required to give?

An employee must notify her employer that she is pregnant, of her expected week of childbirth (EWC) and of the date on which she wishes to start her maternity leave. The employee must provide this information by the end of the 15th week before her EWC. She has the right to change her mind about the date on which she wants her maternity leave to begin, but must notify her employer of the revised start date at least 28 days before the day in question.