Infants change rapidly, and though boys and girls differ in development later in life, their muscle development during the infant stage progresses at the same rate. The difference in the physical development in boys and girls does not become evident until they are of elementary school age.
Personality
Two infants of the same age can be very different in personality. These personality differences at times may have an influence on the timing of displayed muscle development. Where one child may desire to constantly move, another may be content to stay in one place. The child that wants to move may scoot or crawl sooner than the content child, due to his personal desire. This is important to remember when comparing infant development, especially between boys and girls. The standard for "normal" is different for every child, but most children reach certain milestones within a similar given time frame.
0-3 Months
Your newborn will have very little control over her movement, but her muscle development and this control will increase rapidly. During this time period, your baby will start to develop the ability to hold his head straight while looking at an object when lying on his back. You may also notice him pushing up his head and chest with support from his arms when on his stomach. Within a short period your infant may be able to roll from his side to his back. Additionally, when you hold your child standing on a hard surface, she will learn to push down with her legs.
4 to 7 Months
From age 4 to 7 months, your infant will start sitting while supporting himself with his hands, moving on to sitting completely unassisted. When held with feet against a hard surface, your infant will begin to support her whole weight on her legs. Progressing from a side to back roll, she will learn how to roll over completely during this time period. Last, your infant will now become much more aware of his hands. He will learn to reach with one hand, transfer objects from one hand to another and use his hands to rake objects.
8-12 Months
Your infant will become considerably more mobile during this time period, as she has already learned to roll over, she will soon learn to crawl and possibly walk. Infants also learn how to put themselves into the sitting position unassisted during the 8- to 12-month period. Children often pull themselves to a standing position now and even begin to walk with support. Prior to walking, your infant will begin to stand freely, as you may notice him letting go of furniture and standing momentarily on his own. Note that not all infants walk before 1 year of age. Even if your child begins to take a few steps, she may not walk fully until after she turns 1.
Your Child
During infancy, there is no noticeable difference in the muscle development between boys and girls. The milestones for the first year of life are the same for both sexes, though the point at which individual children reach the milestones will vary. If you are worried about your child it is always best to consult your physician. Your child's doctor will be best familiarized with your child, you and your family history and will be able to give you the best opinion on your child's individual muscle development.
References
- Babycenter: Raising Boys and Girls: Differences in Physical Development
- National Network for Childcare: Infant Development
- MayoClinic.com: Infant Development: Birth to 3 Months
- CDC: Important Milestones by the End of Three Months
- CDC: Important Milestones by the End of Seven Months
- CDC: Important Milestones by the End of One Year
