Understanding Infant Development Milestones with Bayley Scales

The Bayley Scales of Infant Development (BSID) are widely used to assess the developmental functioning of infants and young children. They evaluate various domains, including cognitive, language, motor, social-emotional, and adaptive behavior. Motor development milestones, such as turning over or pulling to stand, are key indicators assessed by such scales.

Analysing Statement I: 3 Months - Turns from back to the side

Around the age of 3 months, infants are developing greater control over their bodies, particularly their neck and upper body. While rolling completely over (back to tummy or tummy to back) typically happens later, around 4 to 6 months, turning from the back to the side is a developmental step that often occurs around the 3-month mark. This involves coordinating head and trunk movements to shift weight and turn partially.

Infants at 3 months are usually able to:

• Lift head and chest when lying on stomach.
• Hold head steady.
• Stretch out legs and kick.
• Open and shut hands.
• Bring hands to mouth.
• Push down on legs when feet are placed on a hard surface.
• Turn from back to the side.

Therefore, the milestone of turning from back to the side is considered a typical developmental skill emerging around 3 months of age and is consistent with assessments like the Bayley Scales.

Analysing Statement II: 9 months - Raises itself to a standing position

By 9 months, infants have significantly advanced gross motor skills. They are often sitting independently, crawling, and starting to explore upright movement. Pulling themselves up to a standing position, usually by holding onto furniture or other stable objects, is a common milestone achieved around this age. This skill requires strength in the legs and trunk, as well as balance and coordination.

Infants at 9 months are often able to:

• Get into a sitting position without help.
• Sit without support.
• Crawl.
• Move from sitting to crawling or lying on belly.
• Use hands and knees to crawl.
• Pull up to stand.
• Walk holding onto furniture (cruising).

The ability to raise oneself to a standing position is a well-established milestone for 9-month-old infants and is a key motor skill evaluated in developmental assessments like the Bayley Scales.

Conclusion

Based on typical infant development patterns assessed by tools such as the Bayley Scales of Infant Development, both statements represent age-appropriate motor milestones:

• Turning from back to the side is expected around 3 months.
• Raising oneself to a standing position (pulling to stand) is expected around 9 months.

Thus, both pairs are correctly matched according to standard infant developmental timelines measured by instruments like the Bayley Scales.