Actually that's not true, Dolores. I believe that you can get this at any time up to the child turning 18.
You must first get a "Consular Report of Birth Abroad" issued by the US Consulate in Santo Domingo in order to gain US Citizenship for your child. Here is the process, and the checklist of documents:
Consular Report of Birth Abroad
This process is a grinding one, especially if you are not married. If you are not married to the mother of your child, expect to be required to get a DNA test to prove your fatherhood. You must also use THEIR lab to do this test, so don't get it done before you go to the consulate, thinking you will save time or money. At some point you will need to physically bring the child in too, which is tough to do with a very young one.
After running around for a day or two getting documents, and then getting them legalized, then you go back for an interview (they set the date or tell you the days you can return). You have to also present all of YOUR US documents to prove that YOU are a US Citizen. Also, bring photos of you and the mother at all stages, etc. (if you don't have any photos, start snapping them, bud - just something that may help.
AFTER the US Consulate issues the Consular Report of Birth Abroad certificate, they will issue a SS card and a passport to your child as part of the process. Once you get that birth certificate, put it away somewhere safe, like a bank vault, because they will NEVER issue another replacement certificate - too much fraud here inthe DR apparently.
I have gone through this process, and believe me, I now understand why they put bulletproof glass in front of their "interrogators". I would have liked to strangle them, especially after their stupid little pencil-necked geek asked for "my passport so they could prove I had access to the female" (his friggin words exactly) The axxhole was talking about my wife, whom I had married long before she became pregnant.
I would also like to strangle anyone who says that US citizenship is "automatic" for a child born overseas to a US citizen. Sure it is, after you go through their obstacle course. I, for one, am going to do my best to try and convince my children to renounce it before they turn 18. In the meantime, it makes it a bit easier for our family to travel. After all, all a US passport is, is a TRAVEL document. (for now , at least).
You can bring your US passport to the hospital so they will record it on the Dominican birth certificate. After that, you will need to go through the process. And in the future, if you plan on taking your chiild to the US, you will either need to take along Mama, or else go back through yet another process to have her agree legally, with yet another certificate issued, that yes, you can take your child to another country without her.