These two words both appear to have the meaning "to give birth" or "to produce". However, what is the difference between the two kanji used?
I originally assumed that 生む meant "to give birth" and 産む meant "to produce", but looking at some example sentences, they seem to be used interchangeably. What is going on there?
Check out this site for some kanji etymology. I've posted the results there.
産 : 生 (Type 2 Phonetic) birth; life + an abbreviated form of 彦 (handsome/well-formed) → (well-formed), locally grown, life-sustaining product → produce; production; local product/material (that sustains life) → one's birthplace → childbirth.
生 : SIS shows an abbreviated form (Type 8 Phonetic) of 艸 grass/plant + 土 earth → fresh, slender grass shoots → birth; life → new; fresh; sprout; raw; alive; by nature; youth; unripe; pure; bear fruit; spare a life; bring back to life; make use of; make a living; be/remain valid; arrange flowers/plants; grow; undiluted.
Funny enough I just saw these two kanji used in a short story by Kenzaburo Oe this evening while studying. In the story なぜ子供は学校に行かねばならないのか, the narrator uses the 産む when referring to his mother's speech, where 生む is used in the passive form (生まれる）. Both are talking about giving birth, but its interesting to think about how the usage of 産 in this case does refer more explicitly to the production of a child.
Although that alone, even combined with the kanji etymology, isn't conclusive, but it seems to me like you're on the right path when viewing 産 as more related to production whereas 生 is inherently more related to life, as a general concept, e.g. 生物、[生]{い}きる、生活
うむ and うまれる should be written with 産 only if it refers to the (punctual) act of a mother giving birth to a baby or, in the case of non-mammals, a female laying an egg or a young hatching from an egg. 生 can also be used for that, but it covers a much broader range of meanings and is used for all other senses.
The reason うまれた is often written with 生 is that it is used to refer to the beginning of one’s life in an abstract sense, rather than the concrete instance of emerging from the mother’s body or, to use a passive form, being delivered. 産 may be used to stress the latter sense.
元気な男の子が産まれた。
cf.
私はアメリカで生まれた。
産みの苦しみ may also be used for a thing, but this should be understood as a figurative usage in reference to the pains a mother goes through when delivering a baby.
Here are a few references.
