Payment of Maternity Benefits - please clarify "at least 80 days in the past 12 months"

We are an NGO and have an employee who has joined in May 2018. She is currently pregnant. Will she be eligible for maternity benefit in reference to the rule:
Eligibility: As per the Act, to be eligible for maternity benefit, a woman must have been working as an employee in an establishment for a period of at least 80 days in the past 12 months. What does 'In the past 12 months' mean. Please clarify.

Hello Annonymous, The employee will be eligible for maternity benefit if she has worked for 80 days immediately preceeding the date of delivery in the preceeding 12 months.