Updated: May 1
Amenorrhea is defined as the absence of menstruation. It may be classified into two types - primary and secondary. Primary amenorrhea occurs when one has not had the first menses by the age of 16 years. Secondary amenorrhea occurs when one has had menstruation before, but has not had one for at least 6 months. Oligomenorrhea refers to infrequent menstrual cycles occurring less than 6 to 8 cycles a year. In this article, we will discuss mainly secondary amenorrhea.
The science behind
To understand how menstruation occurs, we must first learn about some basic science and body parts involved. The hypothalamus, which resides in your brain, sends signals called the gonadotropin-releasing hormones (GnRH) to a gland called the pituitary gland. The pituitary sits at the base of your brain just behind your nose. When it receives signals from the hypothalamus, it then sends its own signals (called the luteinising hormones (LH) and follicle stimulating hormones (FSH)) to the ovaries which then produces sex hormones oestrogen and progesterone. Oestrogen and progesterone go on to regulate your menstrual cycles. This is known as the hypothalamus-pituitary-ovarian (HPO) axis. The photo below illustrates this cycle.