The U.N. guidelines for genocide extend beyond suppression of birth. You typically have to meet several of the guidelines, "with intent to destroy," for the UN to classify policy as genocidal. You can find them here:
https://www.un.org/en/genocideprevention/genocide.shtml
And even the U.N. guidelines are controversial in genocide study circles due to the ongoing academic debate on intent.
Edit: Intent is the most fierce academic discussion in genocide studies. It's the first major academic topic introduce in Genocide: A Comprehensive Introduction (Adam Jones), which is the standard introductory book. Here's a collection of books, not even articles, primarily concerned with intent:
* With Intent to Destroy: Reflecting on Genocide
* The Khmer Rouge and the Crime of Genocide: Issues of Genocidal Intent with Regard to the Khmer Rouge Mass Atrocities
* A Collective Theory of Genocidal Intent
* On the Nature of Genocidal Intent
Not to mention dozens of articles, symposia, proceedings, debates, book chapters, reviews, and more. The UN-defined "with intent to destroy" has become the most notorious and controversial phrase in genocide studies. Adam Jones pp 11-39, 49-51 is my recommended reading for a primer on the subject. It's online for free. [0]
[0] http://www.genocidetext.net/gaci_origins.pdf