"He raised his children alone for his wife died in childbirth." Long answer
: although you may indeed use "for" instead of "as" in your example sentence, be aware of the following two points:
1. When "for" has the meaning "because" - as in this case - it is a conjunction, not a preposition.
2. This usage, while perfectly correct, is a little dated, not to say stilted (a study of the former British prime minister John Major's speaking will reveal hundreds of examples).