Babies’ skin changes rapidly; during puberty skin becomes adult; and at maturity women’s skin ages faster than men’s one.
Skin colour is one of the main differentiating features between people of different ethnic origins. Sex and age are further differentiating factors: male skin is unlike female skin and baby skin is very different from adult skin. When they come into the world, newborns have deep red skin, with bluish tones in their hands and feet. The colours darken slightly before the baby draws its first breath. The entire body of newborns is also covered with a waxy substance that is removed with their first bath; called vernix caseosa, it protects them against the amniotic fluid in the uterus. Newborns also have fine, soft hairs covering the scalp, face and back that disappear within the first few weeks.
These features are common to all babies, but some skin features depend on the length of gestation. Thus, premature babies have thinner and more transparent skin than babies born closer to their due date. The skin tone of all babies lightens two days after birth and may also become dry and flaky. As infants are very sensitive to changes in temperature, cold makes their hands and feet turn blue and crying makes their skin go red.
Skin problems are common in babies, including milk spots on the face - small whiteheads that clear up spontaneously – and mild acne, caused by residual maternal hormones in the bloodstream. The acne tends to disappear after a few weeks, as does toxic erythema, a generalized rash of small pustules that erupts after birth.
By far the most common skin problem in infants, however, is nappy rash, which is caused by the dampness of urine and faeces in contact with the skin. The best treatment is to change nappies promptly and apply a zinc oxide-based cream to irritated skin.
Why does women’s skin age faster?
The clear physiological differences between men and women are also reflected in the skin. A study by researchers at the University of Granada (Spain) found that men have thicker skin and that their skin thins gradually over the years, whereas women’s skin only begins to thin around the age of 50.
Men also have higher levels of collagen, a protein essential to organ and tissue formation that also delays the skin’s ageing process. Women's lower collagen levels explain why women appear to age earlier than men.
The production of sebum - an oily substance that protects the skin surface - also differs in the two sexes. The sebaceous glands, which are connected to the hair follicles, are active in men until around the age of 80; in women, however, decreasing androgen levels after menopause lead to lower sebaceous gland secretions, possibly explaining why women experience drier skin at an earlier age than men.
Skin acidity, measured on the pH scale, is also different in men and women. Male skin is slightly more acidic so it needs greater hydration than women’s skin, as confirmed by the University of Granada study mentioned above. Shaving and the lack of daily care routines further increase the acidity of male skin.
The gap narrows in puberty
So what happens in puberty? A study by the Shiseido Life Science Research Center in Japan analysed the properties of the skin surface layer, the stratum corneum, in children approaching adolescence and their mothers.
The scientists found that the skin of children was less hydrated and that the barrier function of the stratum corneum was weaker in the children than in their mothers; furthermore, although much stronger on the cheeks, this barrier weakened as the children approached puberty.
The amount of lipids in the surface skin layer remained low until the age of 13. By 14, however, levels came close to those of the adults. This study clearly demonstrated that children’s skin is very different from adult skin.
However, none of the variable skin features in adults, women, men, teenagers, children and babies change the fact that the skin is our protective shield against the outside world.
Medline Plus (US National Library of Medicine)