The following signs would warrant fuher evaluation of developmental status in a healthy 12 weeks old infant:
A baby with 12 weeks of age should vocalise. If not, baby should warrant further evaluation. Ref: Kligman, Behrman, Jenson, Stanton (2007), Pa II, "Growth, Development and Behavior ", In the book, "Nelson's Textbook of Pediatrics", Volume 1, 18th Edition, New Delhi, Pages 43-47
Dose not vocalize
Dose not babble
Dose not raise head up to 90deg
Dose not transfer a bright red ring from one hand to the other, even when the ring is directly placed in the hand of child