Precocious puberty is characterised by excessive growth in height and weight in girls by the age of 8 and in boys by the age of 9. In girls, the specific signs are breast development, changes in the external genitalia, the appearance of pubic and axillary hair, and the onset of menstruation; in boys, the signs are changes such as increased testicular volume, growth and thickening of the penis, the appearance of beard, pubic and axillary hair, a low voice, and seminal emission.