First apply for a marriage certificate, and then apply for a birth permit. You can apply on the same day. Just provide both parties' ID cards, household registers and marriage registration photos. You do not need a birth permit to register, but the following materials are required:
 1. The birth certificate of the newborn (if there is an auxiliary company, the police station will take it away)
 2. The original and photocopy of the household registration book of both parents (or household registration certificate)
 3. ID cards and copies of both parents
 4. Parents' marriage certificate
 5. Go to the local police station where the father or mother is registered.
 Article 5 of the Marriage Registration Ordinance
 Article 8 of the Decision of the Central Committee of the Communist Party of China and the State Council on Implementing the Comprehensive Two child Policy Reform and Improving the Management of Family Planning Services