I am not sure what kind of visas they have but there are a couple of mid-wife's operating in Bali. Kim Patra from Australia is one:
https://www.facebook.com/CHCBali/ and Robin Lim runs Bumi Sehat foundation:
Bumi Sehat Foundation | Gentle Birth for a Peaceful Future Maybe they could give information about visas and such. Also try contacting the big hospitals such as BIMC and Siloam. Unfortunately Indonesia does not want foreigners working in the medical industry here. All of the foreign chiropractors for example were just booted out of the country.