General Medical Information

Normal Growth and Development of the Genitalia in Infancy and Childhood

Andrew S. Cook

Changes that occur in the prepubertal female genitalia are a reflection of both the changes in the hormonal environment and the physical growth of the child. The genitalia of the newborn and child are hormonally responsive. At birth, the newborn is under the influence of estrogen via passive transmission across the placenta from the mother. The effects of this hormonal stimulation usually resolve within the first 6 to 8 weeks of life. The most common hormonally related changes include vulvar edema, vaginal discharge, vaginal bleeding, and breast enlargement. The external genitalia of the newborn are swollen and edematous. The hymen usually is thickened and prominent, protruding at the introitus. The hymen can remain thick and redundant as a result of hormonal stimulation for up to 2 years after birth. Changes occur in hymenal configuration in approximately two thirds of infants between birth and 3 years of age.

The vaginal epithelium of the newborn is thickened with glycogen-rich cells in response to estrogen stimulation. The estrogen response also is reflected in the increased number of superficial cells present on the maturation index. The newborn physiologic vaginal discharge is the same as that seen in women in the reproductive age group. About 10% of female infants will experience withdrawal vaginal bleeding in the newborn period. A significant number of newborn infants experience some enlargement of the breast tissue by the fifth or sixth day. Approximately two thirds of these infants will secrete a colostrum-like fluid followed by small amounts of milk. Secretion has been reported to persist up to 1 year.

These findings are much less pronounced in the premature infant. The most prominent feature of the female genitalia in the premature infant is the relatively large clitoris. This is a normal finding, but it is a potential cause for concern to the unsuspecting parent or physician.

Once out of the neonatal period, the child enters a time of relative quiescence until puberty approaches. This time period is influenced primarily by the physical growth of the patient. The uterus undergoes regression from its hormonally influenced size at birth. The initial size of the uterus is not regained until the patient is 5 years old.