Newborns born before 37 weeks are considered premature, and often have distinctly red skin. This appearance is a normal part of their underdeveloped physiology. The redness stems from several biological factors unique to premature infants, reflecting their early arrival and the immaturity of various bodily systems.
The Transparency of Premature Skin
The skin of a premature baby is significantly thinner and more delicate compared to that of a full-term infant. This increased transparency is a primary reason for their red appearance. The outermost layer, the epidermis, and the underlying dermis are less developed in preterm babies, with fewer cell layers. The stratum corneum, the skin’s protective outer barrier, begins to develop around 15 weeks but only forms a functional barrier by about 34 weeks. In premature infants, especially those born before 32 weeks, this layer may consist of only a few cell layers (2-3 layers at 28 weeks), unlike the 10-20 layers found in full-term babies.
This deficiency in skin layers means underlying structures are more visible. Additionally, premature babies have minimal subcutaneous fat, which is the insulating layer of fat beneath the skin. The absence of this fat layer further reduces the skin’s opacity, allowing the blood vessels and circulating blood beneath the surface to show through more prominently, contributing to the red hue. This thin, translucent skin is particularly noticeable in babies born before 34 weeks.
Blood Flow Close to the Surface
The circulatory system of a premature infant also plays a role in their red skin tone. The tiny blood vessels, capillaries, are often more numerous and situated closer to the surface of the skin than in full-term babies. This proximity allows the color of the blood flowing through them to be easily seen.
Furthermore, the immature circulatory system in premature infants can lead to more superficial blood flow. Studies indicate that microvascular blood flow can be significantly higher in preterm compared to term newborns. While the overall systemic blood flow in extremely premature infants might initially be lower immediately after delivery, the distribution of blood flow within the skin can still contribute to its visible redness. The smaller body size of premature infants means their blood vessels are more concentrated, enhancing their visible presence just beneath the skin’s surface.
Understanding Skin Color Variations
While a generalized red appearance is common and normal for premature infants, other skin color variations can occur. Jaundice, a yellowish discoloration of the skin and eyes, is common in newborns, especially premature babies. This yellowing happens due to an excess of bilirubin, a yellow substance produced when red blood cells break down, which the immature liver of a newborn may not process quickly enough. Unlike redness, jaundice indicates a buildup of this pigment.
Other benign, temporary skin changes can also be observed. Acrocyanosis, a bluish tint to the hands and feet, is normal in newborns, including preemies, immediately after birth and can recur if the baby is cold. This is due to immature blood circulation prioritizing vital organs over extremities. Mottling, a blotchy, marbled pattern on the skin, can also appear, particularly when a baby is cold. This temporary pattern is harmless and results from immature circulatory and nervous systems’ adjustment to temperature changes. These distinct color changes are transient and differ from the overall redness characteristic of prematurity.