Uterine contractions are muscle contractions of the uterine smooth muscle that occur during the menstrual cycle and labour. Uterine contractions occur throughout the menstrual cycle in the non-pregnant state and throughout gestation. Throughout menstrual cycle
Uterine contractions that occur throughout the menstrual cycle, also termed endometrial waves or contractile waves, appear to involve only the sub-endometrial layer of the myometrium. Follicular and luteal phase
In the early follicular phase, uterine contractions in the non-pregnant woman occur 1—2 times per minute and last 10–15 seconds with a low intensity of usually 30 mmHg or less. This sub-endometrial layer is rich in estrogen and progesterone receptors. The frequency of contractions increases to 3–4 per minute towards ovulation. During the luteal phase, the frequency and intensity decrease, possibly to facilitate any implantation. Menstruation
If implantation does not occur, the frequency of contractions remains low; but at menstruation the intensity increases dramatically to between 50 and 200 mmHg producing labor-like contractions. These contractions are sometimes termed menstrual cramps, although that term is also used for menstrual pain in general. These contractions may be uncomfortable or even painful, but they are generally significantly less painful than contractions during labour. Painful contractions are called dysmenorrhea. Directionality of contractions
A shift in the myosin expression of the uterine smooth muscle has been hypothesized as arising for changes in the directions of uterine contractions during the menstrual cycle. Labour
Uterine contractions are part of the process of natural childbirth (i.e., not by Caesarean section). During labor, uterine contractions changes from episodic and uncoordinated to highly-coordinated.
"Blue Man Seeks Acceptance" about another victim of argyria due to colloidal silver. "Man Turns Blue", by Duncan Hooper, telegraph.co.uk, Dec. 21, 2007. "This Man Turned Blue (video)", NBC Today Show, Matt Lauer interview, aired January 7, 2008. Chemistry behind the ‘blue man’ unlocked", by Josh Howgego, Chemistry World, 1 November 2012.