Final answer:
Infants are born with wet skin that may have vernix, lanugo, and show variations in hair presence. Their skin development continues post-birth, with changes in body proportions and the development of their sensory abilities, including touch and hearing. Variation exists in the timing of these developments, but the sequence is usually consistent.
Step-by-step explanation:
At birth, the skin of a newborn is typically wet, possibly displaying streaks of blood, and often coated with patches of waxy white vernix. The presence of vernix, which is a protective substance that also moisturizes the skin, varies from one infant to another. In addition to vernix, newborns might have peeled skin on areas such as the wrists and ankles and may exhibit a fine, colorless hair called lanugo, which typically disappears within the first few weeks postpartum.
The development of the skin continues as the infant grows, with the physical proportions of the newborn, including a relatively larger head size, changing over time. The protective fontanels in the skull enable the head to compress slightly during birth and eventually ossify. In terms of growth, a healthy infant will likely triple their birth weight and double their length by the first birthday. Moreover, sensory development is also progressing, with newborns possessing well-developed senses of touch and hearing, despite their vision and color perception not being fully developed yet.
In the womb, the fetus is covered by lanugo and vernix caseosa during mid-pregnancy, both of which play critical roles in protecting and preparing the infant's skin for life outside the womb. By the end of the first year, the significant milestone of teething commonly occurs, with deciduous teeth starting to emerge around six months of age.
The timeline for these skin development milestones can vary among infants, but the sequence of growth and development typically remains consistent.