Moro's reflex stas during intrauterine life. Persistence of Moro's reflex is abnormal beyond the age of:

The Moro reflex is present in normal infants. A sudden stimulus (eg, a loud noise) causes abduction and extension of all extremities, with extension and fanning of digits except for flexion of the index finger and thumb. This is followed by flexion and adduction of the extremities. Moro's reflex disappear at three month of age and persistence of this reflex beyond three months is abnormal. Ref: Essential paediatrics by OP Ghai, 6th edition, Page 146.