Applying I-130 for first time

Hello, Im a U.S citizen and recently got married to someone who lives abroad (my birth country). I recently made birth certificate in that country because I’ve been living in U.S for decade’s, so there was no reason to make one beforehand. The lawyer I contacted to apply for the form wants me to make a notarized document explaining why I registered my birth certificate so late. The mayor of that city refused to sign the document, saying it’s not their fault birth certificate was registered late. Do I really need it when applying I-130? Is there alternative to it? Thanks.