Can I apply for an extension of stay in Thailand due to pregnancy with a letter from my doctor?

You will need a medical certificate signed by your doctor requesting Thai Immigration grant you either 60 or up to 90 days Medical Extension due to your pregnancy and unable to travel...you are under Medical Care.

Take that's along with the usual forms for an extension...fee 1,900 Thai baht.

For Medical Extension

You need ONLY:

-passport

-copy of passport front page

-copy of stamp/visa page

-copy of TM6 form arrival card

-filled TM7 form extension application

-medical certificate from doctor

-two photos

Possibly TM30 proof of filing

Just so you know

You do NOT have a 30 day visa on arrival :O (because there is no such thing),

if you showed up here without having bought a visa from a thai consulate before you got here and were stamped in free for 30 days you came in on a 30 day visa exempt entry stamp :)

you COULD go apply for an extension of stay based on medical reasons and it could be granted for up to 90 days at a time.