Does an employee who wishes to exercise her right to statutory maternity leave have to give her employer all the required information at the same time?

To take statutory maternity leave an employee must advise her employer of her pregnancy, the date on which she wishes to commence her maternity leave, and the expected week of childbirth (EWC) by the end of the 15th week before the EWC. However, she is not required to provide all this information at the same time. Health and safety guidelines advise that employers should encourage employees to provide them with notification of pregnancy as soon as possible so that health and safety protection begins to apply.