N.Y. Fam. Ct. Act § 517

§ 517. Time for instituting proceedings. Proceedings to establish the\npaternity of a child may be instituted during the pregnancy of the\nmother or after the birth of the child, but shall not be brought after\nthe child reaches the age of twenty-one years, unless paternity has been\nacknowledged by the father in writing or by furnishing support.\n