True labour pains is represented by: September 2006
**Core Concept**
The question is testing the student's knowledge of the characteristics of true labor pains, which are a crucial aspect of obstetrics. True labor pains are a physiological process that involves the contraction of the uterus, causing the cervix to dilate and the fetus to move down the birth canal.
**Why the Correct Answer is Right**
True labor pains are characterized by a regular, progressive pattern of contractions that become stronger and closer together over time. This is in contrast to false labor pains, which are irregular and may not cause the cervix to dilate. The uterine contractions in true labor are caused by the action of oxytocin, a hormone that stimulates the myometrium to contract. The contractions are mediated by the oxytocin receptors on the uterine smooth muscle cells, which trigger a cascade of intracellular signaling pathways that lead to muscle contraction.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because false labor pains can also cause contractions, but they are irregular and do not lead to cervical dilation.
**Option B:** This option is incorrect because preterm labor pains can be similar to true labor pains, but they occur before 37 weeks of gestation and may not be accompanied by cervical dilation.
**Option C:** This option is incorrect because contractions in early pregnancy can be caused by a variety of factors, including implantation of the embryo, but they are not a characteristic of true labor pains.
**Clinical Pearl / High-Yield Fact**
A classic sign of true labor pains is the "P441" sign, where the fetal head moves down the birth canal and can be palpated by the healthcare provider.
**Correct Answer: C. Contractions in true labour pains are regular, progressive, and cause the cervix to dilate.**