People in their mid-twenties to mid-forties are considered to be in early adulthood. By the time we reach early adulthood, our physical maturation is complete, although our height and weight may increase slightly. Those in their early twenties are probably at the peak of their physiological development, including muscle strength, reaction time, sensory abilities, and cardiac functioning. The reproductive system, motor skills, strength, and lung capacity are all operating at their best. Most professional athletes are at the top of their game during this stage, and many women have children in the early-adulthood years Boundless, The aging process actually begins during early adulthood.

Early and Middle Adulthood
Early Adulthood
During early adulthood stage an individual reaches physical maturity by the age of This is known as maturation. Adults have reached their peak level of physical strength and their full height and weight by this time. As the adult reaches the end of this life stage, stamina and strength start to slowly decline. The early adulthood stage is when women are most likely to become pregnant. Pregnancy and lactation are key characteristics of early adulthood. During pregnancy, hormones change, and the levels of progesterone steadily increase. Progesterone is responsible for maintaining the pregnancy and is produced by the ovaries, the placenta when a woman is pregnant and the adrenal glands. Oestrogen is needed for the correct development of the foetal organs, including the liver, kidneys and lungs. With a background in industry, Melanie has supported teachers of Health and Social Care through numerous CPD projects and is an experienced examiner.
Adult Human Development
Network Connection Required to View this Feature. Section 1, Article 1 - By the time that individuals are to years-old, their physical bodies have reached maximum growth. Emerging adults are as tall and strong as they are ever going to be. Some of the key physical changes that take place are muscle growth, strengthening of the bones, and body shape changes. Adult development and aging: Biopsychosocial perspectives 4th ed. Hoboken, NJ: Wiley.
Age clocks, or the internal sense of timing of physical and social events, determine the various life stages through which adults pass. Although people age at different rates, the majority of Americans, reinforced by social norms, pass through a series of predictable periods. According to Levinson, the ages of 17 to 45 encompass early adulthood, which he divides into the novice phase 17—33 and the culminating phase 33— The culminating phase 33—45 consists of the settling down 33—40 and midlife transition 40—45 stages. As with any stage theory, these stages are only a guide for the development that normally occurs along a continuum. Not everyone progresses through each stage at exactly the same age.