Hi,

Will the firecrackers sound affect the fetus in womb?

Regards,
Vijay

nope.

Doctors will tell you not to worry but some suggest that you err on the side of caution, especially chronic noise, such as at a noisy job.
There really haven't been any studies, because it would require test subjects to endure loud and harsh noises, and that would be unethical to ask for.
There have been studies involving pleasant music that seem to suggest that the fetus (probably later in the pregnancy, I can't remember) does react by at least acting calm; e.g., less kicking and moving.
There ARE conclusive studies showing that INFANTS react in their sleep to stressful noises like parents arguing loudly. I wish more parents were aware of that.
Sounds Of Arguing Affect Babies' Brains, Even While They're Asleep (http://www.huffingtonpost.com/2013/03/28/sounds-of-arguing-affect-_n_2971911.html)

I think it might depend on how far along the fetus is. How close to the mother. And how the mother reacts.

Watching a controlled fireworks display should have no affect. Throwing some firecrackers near an unprepared mother might have some effect.