Final answer:
It is slightly early but most likely normal for a 10-month-old to show a hand preference. Ongoing observation is appropriate to ensure the child's overall development is on track. A hand preference at this age is not usually cause for concern unless accompanied by other developmental delays.
Step-by-step explanation:
A mother's observation of her 10-month-old boy showing a hand preference for reaching is mildly early but within the scope of normal development. At this stage, infants develop the ability to manipulate objects with greater precision, such as using a pincer grasp, and may start to show a preference, yet it is not a fixed indication of handedness. It is common for children to experiment with both hands as they grow. There is variation in when children show a clear preference, and this typically becomes more evident closer to the age of two or three. As the child develops, the observed hand preference can change or become more defined.
Developmental milestones, such as grasping, sitting, crawling, and walking, occur within a range of ages, and there is considerable normal variation. Hand preference at 10 months could simply be part of this child's unique developmental trajectory. If the child is meeting other developmental milestones and showing no signs of delay in motor or cognitive skills, this isolated observation does not typically warrant concern. However, ongoing observation is sensible to ensure the child continues to make typical progress across all areas of development.
As with toddler Louisa, while some children may start walking by 12 months, it is not unusual for others to walk later. Louisa's concern for her daughter not walking at 14 months shouldn't be alarming, but if there were no progress by 15 to 18 months, seeking advice would be appropriate. Similarly, a hand preference at 10 months may warrant attention only if other developmental delays are present or if the preference seems to limit the use of the non-preferred hand.