Newborn babies normally lose all of their hair within a few months of birth. Most of the time, new hair appears within a few months--with one exception. Since the advent of the "Back to Sleep" campaign, which advocates back sleeping for infants to prevent sudden infant death syndrome, or SIDS, many babies have less hair at the back or side of their head. The constant rubbing against the head from back positioning breaks off the hair.
Normal Hair Loss
All babies lose hair after birth, even those with thick heads of hair. Hormonal changes at the time of birth send hair into a resting phase during which hair doesn't grow but current hair also doesn't fall out. Once the hair enters the growth phase, the old hair falls out all over the head, including the back, and new hair grows in.
Time Frame
Hair loss at the back of the head might not be obvious until the first hair falls out and new hair grows in everywhere but the back of the head.
Causes
Mechanical pressure against the back of the head usually causes bald spots. Less-common causes include fungal infections such as tinea capitus, cradle cap and alopecia areata, an autoimmune condition that causes smooth bald spots, pediatrician and author Alan Greene reports on his website, DrGreene.com
Prevention
Putting babies to sleep on their backs has reduced the incidence of SIDS by 40 percent, Pediatrics for Parents reports, so hair loss at the back of the head shouldn't prevent parents from following the guidelines. During the day, however, varying the baby's position helps relieve pressure. Unfortunately, swings, car seats and bouncy chairs--popular alternatives for placing a baby when awake--put the same pressure on the back of the head. Carrying the baby in a sling, putting him on the floor on a blanket for "tummy time" while playing with him, carrying him upright or sitting him up helps prevent bald spots from developing.
Treatment
Hair normally grows back when pressure on the back of the head is reduced. No special treatment is necessary when a baby loses hair at the back of the head, except to vary positions and supply more time off of the back.
