Primary amenorrhoea

What it is

Puberty runs in a set order, and each step has an age:

• Thelarche: estrogen rises and breasts develop, 10Y
• Pubarche: androgens rise, then pubic and axillary hair, 11Y
• Menarche: estrogen rises and the first menses come, 12 yrs. It is concerning if this is not occurring by 15 yrs, or 2.5 yrs after thelarche.

Primary amenorrhea is no menses by 16 yrs of age in the presence of secondary sexual characters, or no menses by 14 yrs of age in the absence of secondary sexual characters. The two ages are not the same, because a girl with no breast development has had no estrogen at all and cannot be given the longer wait. Secondary amenorrhea is a different thing: no menses for 3 months if cycles were regular, or no menses for 6 months if cycles were irregular. The two ages are asked apart, so they are held apart: with secondary sexual characters present the age is 16 yrs, and with them absent the age is 14 yrs. The pages do not give the same ages. One keeps the two used above; another divides amenorrhoea into primary, failure to start menses by the age of 16 years, and secondary, cessation of established regular menstruation for 6 months or longer; a third sets primary amenorrhea at absence of menarche by age 15 in a girl with normal secondary sexual characteristics, or by age 13 without them.