I got an email from my lawyer stating that "Birth documentation must have been registered within one year after the birth and must comply with the State Department Fees and Reciprocity tables, which specifies documents required and available from each country".
I also checked with dept. of state website and found that birth certificates "Available in the form of notarial certificates, which are secondary evidence. Notarial certificates of birth (Chu Sheng Gong Zheng Shu or Chu Sheng Zheng Ming Shu) for persons living in or recently departed from China are generally reliable, but are best used in conjunction with other evidence. They are most often based upon an AHHR, (Household Record) which is easily susceptible to fraud, especially in villages. Notarial birth certificates for persons long departed from China are most likely based merely upon the testimony of interested parties."