A baby’s hair growth is shaped primarily by genetics, hormones, and nutrition. More than 120 genes influence hair color, texture, and thickness, which is why some newborns arrive with a full head of hair while others are nearly bald. Both outcomes are normal, and the hair your baby is born with will likely change dramatically over the first year.
How Hair Starts Growing Before Birth
Hair follicles begin forming between weeks 9 and 12 of pregnancy, as part of an interaction between two layers of developing skin. By about five months of gestation, these follicles produce lanugo, a fine, soft hair that covers much of the fetus. Lanugo typically sheds before birth, though some babies are born with traces of it on their shoulders and back.
The hair visible on a newborn’s head is a different type, often thicker and darker than what the child will eventually have as a toddler. This birth hair grows during the final months of pregnancy, fueled by hormones the baby receives through the placenta. Those hormones play a big role in why birth hair behaves so differently from the hair that replaces it.
Why Most Babies Lose Their Birth Hair
Newborn hair typically starts falling out around the second month of life, and shedding can continue until about six months of age. This process, called telogen effluvium, happens because of a hormonal shift. While in the womb, the baby is exposed to the mother’s estrogen, progesterone, and other hormones that keep hair in an active growth phase. After birth, those hormone levels drop sharply, pushing many hair follicles into a resting phase all at once. A few months later, the resting hairs fall out.
This is the same mechanism that causes many new mothers to notice their own hair thinning a few months postpartum. For babies, the shedding is temporary. New hair grows in to replace what was lost, though it may be a completely different color or texture.
Genetics: The Biggest Factor
Over 120 genes are involved in determining hair pigmentation alone, and a separate set of genes controls texture, curl pattern, and growth rate. This means there’s no simple inheritance pattern. Two dark-haired parents can have a baby born with light hair, and a baby born with straight hair may develop waves or curls as new hair comes in during the first year or two.
Hair color depends on melanin, the same pigment responsible for skin tone. Babies often produce less melanin in their first months of life, which is why many are born with lighter hair that gradually darkens. Some children’s hair doesn’t settle into its permanent color until age five or six. Texture changes are equally common. A baby born with tight curls may grow into straight-haired childhood, or vice versa, because the shape and angle of hair follicles can shift as the scalp grows and matures.
How Nutrition Supports Hair Growth
Hair is built from protein, and it requires a steady supply of key nutrients to grow. For infants, breast milk or formula provides what’s needed. Iron is particularly important. It was added to infant formulas starting in 1959 specifically to prevent deficiency, and iron-poor diets have long been linked to hair thinning in both children and adults. Zinc, B vitamins, and vitamin D also contribute to healthy follicle function.
For breastfed babies, the quality of the mother’s diet matters. A well-nourished mother produces milk with adequate levels of these nutrients. Once a baby starts solid foods (typically around six months), iron-rich options like pureed meats, fortified cereals, and legumes help support continued hair growth alongside overall development. If your baby’s hair seems unusually thin or sparse well past the first birthday, a pediatrician can check for nutritional gaps with a simple blood test.
Bald Spots on the Back of the Head
Many parents notice a flat, bald patch on the back of their baby’s head and assume it’s from rubbing against the mattress. This is called neonatal occipital alopecia, and for decades, friction from sleep position was considered the main cause. Research tells a different story.
A retrospective study published in the Annals of Dermatology found no significant association between a baby’s sleeping position and the development of these bald spots. Babies who slept on their backs were no more likely to develop the patch than those who slept in other positions. The bald spot appears to be a localized version of the same hormonal hair shedding that affects the rest of the scalp. It’s more closely linked to pregnancy-related factors like gestational age and delivery method than to anything happening after birth. The hair grows back on its own, and the patch is not a sign of damage to the follicles.
Cradle Cap and Hair Loss
Cradle cap, the flaky, yellowish scaling that appears on many babies’ scalps in the first few months, can look alarming, especially when loose hair comes away with the scales. According to the NHS, this hair loss is temporary and the hair grows back once the cradle cap clears. Cradle cap is a form of seborrheic dermatitis caused by overactive oil glands, likely stimulated by lingering maternal hormones. It does not damage hair follicles or cause permanent thinning.
Gently massaging the scalp with a soft brush or a small amount of oil can help loosen the scales. Picking at them aggressively is more likely to irritate the skin than to speed up the process. Most cases resolve on their own within a few months without any treatment.
What You Can (and Can’t) Control
The thickness, color, and growth rate of your baby’s hair are overwhelmingly determined by genetics and developmental timing. No shampoo, oil, or scalp treatment has been shown to make infant hair grow faster or thicker. Shaving a baby’s head, a common folk practice in many cultures, does not change the texture or density of hair that grows back. It only appears thicker because the blunt-cut ends feel coarser than the tapered tips of natural hair.
What you can do is support the conditions for healthy growth. Ensure your baby gets adequate nutrition through breast milk, formula, or age-appropriate solid foods. Keep the scalp clean and handle it gently. Avoid tight headbands or clips that pull on fine baby hair, as repeated tension on fragile follicles can cause a type of hair loss called traction alopecia.
Most babies who appear bald or patchy in the early months have a full head of hair by their first or second birthday. The timeline varies widely, and slower growth is rarely a sign of any underlying problem. Hair follicles are all present at birth. They simply activate on their own schedule.