A child born in China, who has a foreign passport, loses any claim to Chinese citizenship once they leave the country. Before leaving China, though, you have to go to the PSB and get an Exit Permit to take the child out...China regards children born in China as Chinese citizens, regardless of passport, until they leave on a foreign passport.
Actually, I think children under 18 can "piggyback" on your Z visa or Residence Permit, and don't need their own. Spouses may be able to do this, too. I don't think it always applies to Tourist or Business visas, though. I dunno...stuff can change pretty fast. Best bet is to check with your local PSB or Chinese Consulate.