I think that your management wants to avoid the sanction of maternity leave in view of the long leave availed of so far.If the reasons cited by you are genuine, you can go on LOP on medical grounds. Any how, Do not resign at any cost. Don't also apply for LOP more than one month at a time. Each spell of LOP applied for shall be authenticated by medical certificate. It is also very important that you inform the fact of pregnancy in your leave applications to pre empt any possible disciplinary action leading to dismissal.
3rd September 2019 From India, Salem
You better make an application for santion of leave unde MB Act with the medical confirmity that you are pregnant and make a copy to the Asst. Labour Commisioner of the locality of your office establishment.
5th September 2019 From India, Mumbai