For a number of years, I have been interested in newborn infants who scratch themselves. About 20% of normal neonates do this, usually on one cheek or the other, until spontaneous cessation at a mean age of 4 months.
In my observations, I have found significant correlation between such scratching, low parity of the mother, and full-term gestation. The nonscratchers had significantly shorter gestation and their mothers greater multiparity. On follow-up 1 year later, after periodic checks, the only significant difference between 26 scratchers and their matched controls was the greater incidence of skin disorders (mostly atopic dermatitis) in the former group.