The uterus (or womb as it is commonly known) is quite simply an amazing organ. It is a baby’s first home. A place in which a tiny fertilised egg (zygote) has the opportunity to develop into a healthy, thriving human being.
A normal uterus is a hollow muscular organ about the size and shape of a pear but has the ability to expand and stretch considerably to accommodate a growing foetus. In its non-pregnant state the uterus can hold around a teaspoon of liquid. During pregnancy it can expand up to 500 times its normal size!
The uterus is made up of 3 layers
- The perimetrium (the thin outer layer)
- The myometrium, (the strong muscular layer in the middle)
- The endometrium that forms the uterine lining.
The uterus is extremely strong. In fact the uterine muscle (myometrium) is one of the strongest muscles in the body enabling the strong, rhythmic contractions required for childbirth and to a lesser extent, to expel the endometrial lining each month.
The uterus is constantly renewing its lining to prepare for impending implantation of a fertilised egg. This can be seen in the monthly shedding of the uterine lining (endometrium), which occurs each month. In fact the sole purpose of the menstrual cycle is to prepare the uterus for pregnancy.
The endometrium, or uterine lining, is made up of 2 layers, which merge together to appear as one. However they perform very different roles. The basal layer remains intact as a constant cover for the myometrium (uterine muscle). The basal layer changes very little in response to the hormonal fluctuations during menstruation and is not shed during the period. The functional layer on the other hand responds greatly to the monthly changes in hormonal activity and is shed as menstrual blood and rebuilt each month.