Uterine contraction

[1] The pregnant uterus only contracts strongly during orgasms, labour, and in the postpartum stage to return to its natural size.

[3] 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.

[3] Uterine contractions are a vital part of natural childbirth,[6] which occur during the process of labour and delivery, (typically this excludes caesarean section).

[8] As labour progresses, contractions will typically increase in frequency and intensity, which leads to a significant rise in intrauterine pressure.

Some women experience what are commonly called Braxton Hicks contractions before their initial due date, which are characterized as “false labour."

[12] Uterine contractions can be monitored by cardiotocography, in which a device is affixed to the skin of the mother or directly to the fetal scalp.

[13] A type of monitoring technology under development at Drexel University embeds conductive threads in the knitted fabric of a bellyband.

When the fibers stretch in response to a contraction, the threads function like an antenna, and send the signals they pick up to an embedded RFID (radio-frequency identification device) chip that reports the data.

[15] Removal of Ca2+ after contraction induces relaxation of the smooth muscle, and restores the molecular structure of the sarcoplasmic reticulum for the next contractile stimulus.

In these experiments, sections of myometrium are set up in an organ bath system that to measure changes in isometric force production.

Following functional checks to ensure the tissue is physiologically active, compounds can be added to the organ bath in increasing concentrations to create a cumulative concentration-response curve (CCRC).