It appears you have received a request for additional evidence and may need to send more evidence of your relationship. Your baby's birth certificate should be included. You should also hire an attorney to help you.
The answer provided here is general in nature and does not take into account other factors that may need to be reviewed for a more precise answer. You should consult with an immigration attorney before taking any action. The answer here is not intended to create an attorney-client relationship.
You need to answer all information requested in the request for information. Also, you should provide all updated evidence including specifics as to the child's birth etc... It is always advisable to consult with an experienced immigration attorney when answering any RFE. Good luck.
Legal disclaimer: The statement above is provided by CC Abbott is based on general assistance and not intended to be a legal opinion because not all the facts are provided. The person requesting information and all others reading the answer should retain an attorney who is permitted by the state bar within the jurisdiction who can examine the complete facts and provide a legal opinion on your case. All information provided in the above answer and other information provided by CC Abbott does not create an attorney/client relationship within any state of Federal law.
Your best course of action now is to have an attorney review what was filed and what USCIS is asking for to prepare the appropriate response.