Which is a primary sign of labor?

DSSSB Public Health Nurse - 2015

Obstetrics and Midwifery Nursing

Easy

Appeared in: DSSSB Public Health Nurse - 2015

Explanation

Uterine contractions are the primary, involuntary power of labor, responsible for initiating the entire process.
These contractions cause the two critical changes of the first stage of labor: cervical effacement (thinning) and cervical dilation (opening).
The onset of true labor is defined by the presence of regular, progressively stronger uterine contractions that lead to these cervical changes.
Unlike other forces, uterine contractions are independent of maternal control and are driven by hormonal changes, primarily involving oxytocin and prostaglandins.

Option B: Pushing by the mother is a secondary power of labor. It is a voluntary effort that is only effective and encouraged after the cervix is fully dilated (10 cm).
Option C: Intrathoracic pressure is not a sign of labor itself. It is a physiological change that occurs when a person holds their breath and bears down (the Valsalva maneuver), which is part of the pushing effort.
Option D: Abdominal contraction is a secondary power of labor, working in conjunction with maternal pushing. It is a voluntary action to increase intra-abdominal pressure.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiology of Labor: Primary and Secondary Powers as background academic context rather than a clinical decision trigger.
A key nursing role is to assess uterine contractions for frequency, duration, and intensity to determine if a patient is in true labor versus false labor (Braxton Hicks contractions).
Nurses educate patients that true labor contractions become longer, stronger, and closer together over time and are associated with cervical change, whereas false labor contractions are typically irregular and do not progress.
It is critical to instruct a laboring mother not to push until the cervix is fully dilated. Premature pushing can cause cervical swelling (edema), maternal exhaustion, and potential fetal distress.

How to Approach the Question

First, identify the keyword in the question: "primary." This asks for the initial, fundamental event that starts labor.
Next, recall the physiology of labor and the forces involved. Labor is driven by "powers."
Differentiate between the primary power (involuntary, causes cervical change) and secondary powers (voluntary, aids in expulsion).
Evaluate each option against this framework: Uterine contractions are involuntary and cause cervical dilation, making them the primary power.
Options like 'pushing' and 'abdominal contraction' are voluntary efforts that occur later, in the second stage, making them secondary powers.
Intrathoracic pressure is a component of pushing, not a sign of labor itself. Therefore, uterine contraction is the only correct answer.

Concept Tested & Keywords

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E6 Physiology Guyton 4SAE Part 3 p. 66-68

E6 Obstetrics Williams p. 9-26