In infancy, the child’s body is busy making sure all of his or her organs work and learning to control them. The sexual system is no exception. Male babies sometimes have erections during breastfeeding (which can be very disconcerting to the mother), whereas girls have clitoral erections and lubrication (though that is less likely to be noticed). The baby’s body (and mind) has not yet differentiated sexual functions from other functions, and the pleasure of breast-feeding, as well as the stimulation from the lips, mouth, and tongue, create a generalized neurological response that stimulates the genital response.
Self-stimulation is common in infancy, as many infants touch their genitals as soon as their hands are coordinated enough to do so, after about 3 or 4 months (Casteels et al., 2004). Some babies only occasionally or rarely touch themselves, whereas others masturbate frequently. Infants and babies do not masturbate to achieve orgasm, though they clearly derive pleasure from the activity; it is soothing to the baby and may serve as a means of tension reduction and distraction. In fact, in some cultures, it is a common practice for mothers to calm a baby down by stroking the baby’s genitals. Self-stimulation is normal and common at this age, and parents should be more concerned if babies show absolutely no curiosity about exploring their world and their bodies than if they touch themselves.