Pl meet HR team and explain your problem to them(They should be aware of your medical condition by now)
The law provides that 8 weeks prior to due date, concerned person should not be put on heavy duty which can affect the medical condition.One additional month is also provided in the act.All this means the company really cannot make you run in hot sun.
They cannot dismiss you during this period.
Extract of bare act
4. Employment of or work by, women prohibited during certain periods
(1) No employer shall knowingly employ a woman in any establishment during the six weeks immediately following the day of her delivery, 1[miscarriage or medical termination of pregnancy].
(2) No women shall work in any establishment during the six weeks immediately following the day of her delivery 2[miscarriage or medical termination of pregnancy].
(3) Without prejudice to the provisions of section 6, no pregnant women shall, on a request being made by her in this behalf, be required by her employer to do during the period specified in sub-section (4) any work which is of an arduous nature or which involves long hours of standing, or which in any way is likely to interfere with her pregnancy or the normal development of the foetus, or is likely to cause her miscarriage or otherwise to adversely affect her health.
(4) The period referred to in sub-section (3) shall be-
(a) The period of one month immediately preceding the period of six weeks, before the date of her expected delivery;
(b) Any period during the said period of six weeks for which the pregnant woman does not avail of leave of absence under section 6
6 week period has been increased in 2017 to 8 weeks.
So deal with the problem confidently as you have law behind you.May be the matter of few days only where in your maternity leave can be asked.
Be polite and courteous when you speak to them.