In this case, we must first determine the wishes of both parties. If both parties agree to divorce, but the wife needs to sign after giving birth to the child, then the problem can be solved by the following steps:

1. Both parties negotiate and sign a divorce agreement, stipulating various matters of divorce, including property division and raising children.

2. The agreement stipulates the matters that need to be signed after giving birth, and the time and place of signing.

Before signing, you can ask a lawyer to draft an informed consent form, so that your wife can clearly know the significance and consequences of your signature, and then sign the document.

4. When signing, family members or friends of both parties may be invited as witnesses, and the agreement and informed consent form shall be kept in time after signing.

It should be noted that divorce is a matter involving legal procedures and legal effects. It is suggested that both parties consult a professional lawyer before going through the divorce procedure to ensure that their rights and interests are fully protected.