Many expectant parents wonder about their baby’s appearance at birth, including whether they will have hair. The presence and amount of hair on a newborn can vary significantly, prompting curiosity about its origins. This variation is a natural part of infant development, reflecting biological processes during gestation.
Types of Hair Present at Birth
Babies can be born with different types of hair. The most common is lanugo, a fine, soft, and typically unpigmented hair that begins to develop on a fetus around 16 to 20 weeks of gestation. This downy hair covers most of the body, excluding areas like the palms, soles of the feet, and lips.
Lanugo plays a significant role in fetal development by helping to anchor the vernix caseosa, a protective, waxy substance, to the baby’s skin. Together, lanugo and vernix protect the delicate fetal skin from the amniotic fluid and contribute to temperature regulation.
Another type of hair seen at birth, particularly on the scalp, is terminal hair. This is the thicker, more mature, and often pigmented hair that resembles adult hair. Unlike lanugo, which is temporary, terminal hair follicles on a baby’s scalp are patterned for life, with no new follicles forming after birth. Lanugo is eventually replaced by vellus hair—a fine, peach-fuzz-like hair—while terminal hair generally makes up a newborn’s head of hair.
Factors Influencing Hair at Birth
The amount of hair a baby has at birth is influenced by a combination of biological factors, with genetics playing a significant role. Inherited genes from both parents contribute to traits such as hair thickness, color, and growth rate. For instance, specific genes like FGFR2 and EDAR are known to influence hair texture and thickness, meaning if both parents have thick hair, their baby is likely to inherit similar characteristics.
Hormones also exert a considerable influence on fetal hair development. The fetus is exposed to maternal hormones, which, along with those produced by the fetus, contribute to hair growth. Steroid hormones, including glucocorticoids, estrone, and testosterone, are present in the fetal environment.
The timing of hair development and shedding in the womb is closely linked to gestational age. Hair follicles begin to form around 14 weeks of gestation, and lanugo typically covers the body by 20 weeks. Babies born prematurely are more likely to retain lanugo because they have not had sufficient time in the womb for the shedding process to complete. The scalp hair present at birth, known as terminal hair, has usually been growing for five to six months by the time a full-term baby is born. Therefore, the interplay of genetic predisposition, the hormonal environment during gestation, and the baby’s gestational age at birth collectively determine the presence and quantity of hair.
What Happens to Newborn Hair
After birth, the hair a baby is born with undergoes several changes. Lanugo, the fine, downy hair that may cover a newborn’s body, typically sheds within the first few weeks of life, generally disappearing by two months of age. This happens as the baby adapts to the external environment and no longer requires the lanugo for warmth or protection. It is then replaced by softer, less noticeable vellus hair.
The scalp hair present at birth also commonly sheds in the initial months, a process known as newborn hair loss or neonatal alopecia. This shedding often peaks around two to three months of age and is primarily attributed to the significant drop in maternal hormones that the baby received in the womb. These hormonal shifts cause the hair follicles to enter a resting phase, leading to synchronized shedding.
The amount of hair loss can vary greatly; some babies might experience minimal thinning, while others may temporarily become almost bald. This shedding is a normal part of the hair growth cycle and is generally not a cause for concern. Additionally, friction from a baby’s head rubbing against surfaces like crib mattresses or car seats can also contribute to temporary bald spots.
Once the shedding phase is complete, new hair begins to grow in, though the timeline for regrowth differs for each child. Some babies may have a full head of new hair by six months, while for others, it might take up to two or three years. The new hair that grows back can often have a different color, texture, or thickness compared to the hair the baby was born with.
Common Questions About Newborn Hair
Many parents have questions about their newborn’s hair. One frequent question is whether the amount of hair at birth predicts future hair growth. The initial hair a baby is born with often falls out and is replaced by new hair that can differ significantly in color, texture, and thickness.
The presence or absence of hair does not indicate a baby’s health status. Both babies born with a full head of hair and those who are bald are considered healthy and normal, reflecting the wide variation in infant appearance.
A popular belief links maternal heartburn during pregnancy to a baby being born with a lot of hair. While often considered an old wives’ tale, some research suggests a correlation. The proposed biological explanation is that pregnancy hormones, such as estrogen and progesterone, which can cause heartburn, may also play a role in stimulating fetal hair growth.
Some cultures practice shaving a baby’s head with the belief that it will make the hair grow back thicker. This is a misconception, as hair thickness and growth rate are determined by genetics and the hair follicles beneath the skin. Shaving only cuts the hair at the surface, which might create the illusion of thicker hair as it regrows with blunt ends, but it does not alter the hair’s inherent characteristics.