The Traction Response (Pull-to-Sit Reflex)
When you pull a two-month-old baby up by their hands, they demonstrate the traction response (also called pull-to-sit reflex), characterized by initial head lag followed by an attempt to flex the arms and pull themselves forward, though head control remains incomplete at this age.
Understanding the Reflex at 2 Months
At two months of age, when you grasp an infant's hands and pull them from supine to sitting:
- Head lag is normal and expected - the head will initially fall backward as you begin the pull
- The infant will grasp your fingers (palmar grasp reflex, which is present from birth) 1
- They may attempt some arm flexion and shoulder engagement
- Complete head control is NOT expected - significant head lag persists at this age
This is a primitive reflex assessment, not a true "pulling up" motor skill. The persistence of primitive reflexes and their gradual integration is part of normal neuromotor development 2.
When True Pulling Up Develops
Actual independent pulling to stand occurs much later, typically between 8-10 months of age as part of the normal gross motor progression:
- By 9 months: infants should sit well without support and demonstrate motor symmetry 2
- By 18 months: toddlers should stand and walk independently 2
The traction response you're testing at 2 months is fundamentally different from the voluntary motor skill of pulling to stand that emerges in the second half of the first year.
Clinical Significance
Persistence of primitive reflexes beyond expected ages or asymmetry suggests neuromotor dysfunction 2. At the 2-month examination, assess for:
- Symmetry of the grasp and arm flexion response
- Degree of head lag (complete head lag with no attempt at head control would be concerning)
- Quality and strength of the palmar grasp 1
The palmar grasp reflex itself is present from 25 weeks postconceptional age and strengthens through the first 72 hours of life, with notable strength differences between hands in the first day 1, 3.