I want to get a visa based on medical reasons - not being able to fly because of being pregnant. I will enter the 3rd trimester while my tourist visa will still be valuable. Also, I want my husband to get a dependent visa. Ever been in such situation? is it difficult to get the papers from the hospital?

You can get an extension of stay (not a visa) for medical care. You will need a letter from your doctor stating you cannot travel. There may also be some forms that the local immigration office may want done also.

Your doctor will have to request your husbands presence as a caretaker for him to get an extension.

Ubonjoe : Can you give some more details refering to this issue and wether there are cases ( personally) known ?We would highly appreciate .. Greets from Chiangmai

From the official police order.

2.25 In the case of medical
treatment or convalescence
or to look after a patient:
Permission will be granted
for a period of not more
than 90 days at a time.

(1) Confirmation and request has been made by a physician
responsible for the treatment. The Physician must describe the
details of treatment and advised that the illness is a barrier for
travelling.
(2) In the case of looking after a patient, confirmation and request
has been made by the physician responsible for the treatment or
by an embassy or consulate.
(3) Patient Carer, except parents, spouse, children, adopted
children or children of spouse, shall be granted no more than 1
extra person.