Signing a voluntary acknowledgment of paternity is a big deal. Also called a VAP, signing one removes your chance to challenge the paternity of a child with a DNA test. It is a contract, and it can't just be cancelled like a subscription to Netflix. It is important to know this because if you find out later that your woman lied to you, and you're not the baby's father, you've got a tough fight ahead of you.
If you sign a VAP, understand that you only have two years to fight the VAP. And, the only way to overcome the VAP is to hire an attorney, and prove that the contract, the VAP, was signed under duress (a gun held to your head), coercion (she threatened to tell your wife, or your friends something embarassing, and won't do it only if you sign the paper), or fraud (she signed your name on the form, or you can prove she lied to you, without a DNA test).
The VAP has all this information on the bottom of the form. Be sure you understand what you're giving up, and the responsibility that you're taking on before putting your name on a piece of paper that will change your life forever. You have the right to have a DNA test done before signing the form. One can never be too careful.