I attempt at a slightly different view.
The Act says the woman shall actually work for 80 days in the 12 months preceding the expected date of delivery. The expected date of delivery is what a doctor determines based on certain medical factors. The usage of the phrase "expected date of delivery" implies that it is tentative or provisional, and the delivery may happen either before or beyond that date. Therefore, the "expected date of delivery" remains the same for the purpose of the Act, even if the delivery happens in advance of it or beyond it. This is to avoid the contingencies of sanction or withdrawing benefits based on the actual date of delivery, which is a little uncertain and can subject the woman to anxious moments.
Secondly, the Maternity Benefit Act is a welfare legislation and shall advance the cause of women's welfare. Therefore, it shall admit a liberal interpretation that is beneficial to women. Other views are welcome.
B. Saikumar Navi Mumbai