The importance of prostaglandins in the onset of labor is to?

Appeared in: IGNOU PB Bsc Nsg Entrance-2017

Explanation

Prostaglandins (specifically PGE₂ and PGF₂α) are crucial hormones for initiating labor (parturition).
They are produced locally in the fetal membranes and maternal decidua near term.
Their primary function is to stimulate the myometrium (uterine muscle) to contract by increasing intracellular calcium levels.
This action leads to the coordinated, rhythmic contractions that characterize labor.
Additionally, prostaglandins are essential for cervical ripening, which involves softening, effacing, and dilating the cervix to prepare it for delivery.

Option A: Fetal expulsion is the outcome of effective uterine contractions during the second stage of labor, not the initial physiological action of prostaglandins at the onset of labor.
Option C: This is the opposite of the function of prostaglandins. They are uterotonics, which stimulate uterine contractions.
Option D: While uterine contractions are necessary for placental expulsion (the third stage of labor), the question asks about the importance of prostaglandins at the onset of labor.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain The physiological role of prostaglandins in the initiation of labor as background academic context rather than a clinical decision trigger.
Synthetic prostaglandins, such as Dinoprostone (PGE₂) and Misoprostol (PGE₁), are widely used in clinical practice for cervical ripening and labor induction.
Nurses administering these agents must closely monitor the fetal heart rate and uterine contraction pattern for signs of uterine tachysystole (more than 5 contractions in 10 minutes), which can compromise fetal oxygenation.
Tocolytic agents (e.g., terbutaline) should be readily available to counteract uterine hyperstimulation if it occurs.

How to Approach the Question

Identify the key terms in the question: 'prostaglandins' and 'onset of labor'.
Recall the primary physiological function of prostaglandins in the context of childbirth. They are known as uterotonics, meaning they stimulate the uterus.
Evaluate each option against this primary function.
Option B, 'Stimulate uterine muscle activity,' directly describes the main action of prostaglandins in initiating labor.
Analyze the other options to confirm they are incorrect. 'Expulsion of fetus' is a later result, 'reduce uterine muscle activity' is the opposite effect, and 'placental expulsion' is a function in a later stage of labor.

Concept Tested & Keywords

Concept Tested: The physiological role of prostaglandins in the initiation of labor.
Stem keywords: prostaglandins, onset of labor, importance
Lead-in keywords: importance

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E6 Obstetrics Williams p. 13-28

E6 Physiology Guyton 4SAE Part 3 p. 65-67

Practise the full IGNOU PB Bsc Nsg Entrance-2017

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