(1)An employee does not have the right conferred by section 71 unless at least twenty-one days before her maternity leave period commences or, if that is not reasonably practicable, as soon as is reasonably practicable, she informs her employer in writing of—
(a)her pregnancy, and
(b)the expected week of childbirth,
or, if childbirth has occurred, of the date on which it occurred.
(2)An employee does not have the right conferred by section 71 unless, if requested to do so by her employer, she produces for his inspection a certificate from—
(a)a registered medical practitioner, or
(b)a registered midwife,
stating the expected week of childbirth.