Moro's reflex is abnormal after:

The Moro's reflex should not be present after 3-4 months of age. Moro's reflex should be complete and symmetrical by 34 weeks of gestation. Absence of this reflex is abnormal and an asymmetrical reflex may suggest hemiplegia, brachial plexus palsy, or clavicular fracture. This is a primitive reflex in infants. Other primitive reflexes in infants are: Grasp reflex: It is usually present in neonate and may persist upto 6months. Placing/stepping reflex: This neonatal reflex disappears after 6weeks. Asymmetric tonic neck reflex: Obligatory fixed ATNR beyond 4months of age is abnormal and precludes the ability to roll over. Side protective reflex: Emerges after 5months of age. Parachute reflex: It emerges at 7-8 months and is well developed by 10-12months. Ref: A Clinical Handbook on Child Development Paediatrics By Sandra Johnson page 4.