1. Dear member, from the facts as mentioned by you, it is not clear as to since when contribution under ESI Act, 1948 and rules/regulations framed thereunder is being paid by your employer in your case. When you joined the organisation in January, 2015, it is not clear as to whether contribution has been paid from January, 2015 itself. If paid from 4/2015 only onward, then why the gap ?
2. Further, I am doubtful whether you are eligible for maternity benefit under ESI Act in December, 2015 (due date as mentioned by you) or prior to this period. The reasons being that " an insured woman shall be qualified to claim maternity benefit for a confinement occurring or expected to occur in a benefit period, if the contributions in respect of her were payable for not less than seventy days in the immediately preceding two consecutive contribution periods (Section 56(1) of said Act). If you have started contributing w.e.f. 01/04/2015, the first benefit period in your case will start from 01/01/2016 only, (though you can get only medical treatment prior to this date).Please see Regulation 4 of ESI (General) Regulations, 1950.
3. I will, however, suggest you to please visit your appropriate Branch Office of ESIC to which you are attached and discuss the issue with the Branch Manager concerned so that you may be able to get correct position in respect of your eligibility for the said benefit. While visiting Branch Office, please ensure that you have your Pehchan Card ( as issued by Branch Office, ESIC). Further, I hope, you will also ensure to get proper medical certification from the ESIC Dispensary to which you are attached.