It is actually the absence of monthly menstrual bleeding/periods. It can be both physiological as well as pathological.
PHYSIOLOGICAL AMENORRHOEA: can occur before puberty or after menopause or pregnancy or during lactation.
PATHOLOGICAL AMENORRHOEA: can be primary or secondary amenorrhea.
PRIMARY AMENORRHEA: that is menstrual bleeding never occurred like girls below the 14-16 age group. Causes can be due to millennia agenesis or androgen insensitivity that causes no uterus formation or can be due to no estrogen secretion or due to anatomical causes.
SECONDARY AMENORRHEA: that is menstruation cycle has occurred before but now it has suddenly stopped and it didn’t occur for 3-4 months due to various reasons which include pregnancy, decreased secretion of estrogen, hypogonadism, excessive stress.