Just doing some research, it seems early childhood masturbation is not uncommon.
The New York Times:
Quote:Debby Herbenick, a professor at the Indiana University School of Public Health, who has conducted research studies related to child and adolescent sexual expression...If you look at reports from day care providers and parents, Dr. Herbenick said, it is very common to see observations of toddlers touching their own genitals or playing games with their peers that involve some touching. Those reports decrease markedly in slightly older children, she said, from the “older 4s” on up.
“Kids go underground,” Dr. Herbenick said; in studies in which college students are asked to recollect sexual behavior from childhood and adolescence, there are lots of recollections of that behavior from 5 to 9. They’re still doing it, but they have learned to keep it private.
Why Is Children’s Masturbation Such a Secret?From the annals of Saudi medicine
Quote:BACKGROUND AND OBJECTIVES:
Few studies have explored the hormonal triggers for masturbation in infants and young children. Thus, we aimed to study the sex hormones and clinical profiles of masturbating infants and young children.
METHODS:
This case-control study involved infants and young children who masturbate and were referred to three pediatric neurology clinics between September 2004 and 2006 (n=13), and a similar control group. All children underwent basic laboratory investigations prior to referral. Other tests included electroencephalography (n=8) and brain neuroimaging (n=9). We measured dehydroepiandrosterone sulfate, 17-hydroxyprogesterone, free testosterone, estradiol, dehydroepiandrosterone, sex hormone-binding globulin (SHBG), and androstenedione in all participants.
RESULT:
The median age at the first incident was 19.5 months (range, 4-36 months); the median masturbation frequency, 4 times/day; and the median duration of each event, 3.9 min. The subjects masturbated in both prone (n=10) and supine positions (n=3); two subjects used the knee-chest position. All subjects showed facial flushing; 6, friction between the thighs; 5, sweating; 9, sleeping after the event; and 12, disturbance on interruption. EEG was abnormal in one of eight subjects tested, and neuroimages were normal in all of nine subjects examined. The case and control groups had comparable levels of all sex hormones, except estradiol, which showed significantly lower levels in the case group (P=.02).
CONCLUSION:
Masturbation in children seems to be associated with reduced estradiol levels, but not with other sex hormones. Further studies are needed to confirm our findings
Infantile and early childhood masturbation: Sex hormones and clinical profileSummit Medical Group
Quote:WHY DOES MY CHILD MASTURBATE?
Occasional masturbation is a normal behavior of many toddlers and preschoolers. Up to a third of children in this age group discover masturbation while exploring their bodies. Often they continue to masturbate simply because it feels good. Some children masturbate frequently because they are unhappy about something, such as having their pacifier taken away. Others are reacting to punishment or pressure to stop masturbation completely.
Masturbation has no medical causes. Irritation in the genital area causes pain or itching; it does not cause masturbation.
HOW LONG DOES IT LAST?
Once your child discovers masturbation, he or she will seldom stop doing it completely. Your child may not do it as often if any associated power struggles or unhappiness are remedied. By age 5 or 6, most children can learn some discretion and will masturbate only in private. Masturbation becomes almost universal at puberty in response to the normal surges in hormones and sexual drive.
WILL MASTURBATION CAUSE PROBLEMS LATER IN LIFE?
Masturbation does not cause any physical injury or harm to the body. It is not abnormal or excessive unless it is deliberately done in public places after age 5 or 6. It does not mean your child will be oversexed, promiscuous, or sexually deviant. Only if adults overreact to a child's masturbation and make it seem dirty or wicked will it cause emotional harm, such as guilt and sexual hangups.
MASTURBATION IN PRESCHOOLERSThe list goes on.