Which hormone is responsible for dilatation of the cervix in first stage of labour?

RRB Nsg Superintendent -29 April 2025 (Shift-1st)

Obstetrics & Gynaecology

Easy

Appeared in: RRB Nsg Superintendent -29 April 2025 (Shift-1st)

Explanation

Estrogen levels rise significantly towards the end of pregnancy, creating a hormonal environment that favors the onset of labor.
It is a key initiator that stimulates the fetal membranes and decidua to produce and release prostaglandins.
Prostaglandins are directly responsible for the biochemical process of cervical ripening, which includes softening, effacement (thinning), and initial dilatation.
Estrogen also upregulates the number of oxytocin receptors in the uterine muscle, dramatically increasing its sensitivity to oxytocin, which drives the strong contractions necessary for progressive cervical dilatation.

Option A: Testosterone is the primary male sex hormone (androgen) and does not play a physiological role in initiating or progressing labor in females.
Option C: Follicle-Stimulating Hormone (FSH) is a gonadotropin whose primary function is to stimulate the growth and maturation of ovarian follicles at the beginning of the menstrual cycle. Its levels are suppressed during pregnancy.
Option D: Luteinizing Hormone (LH) is a gonadotropin that surges mid-cycle to trigger ovulation and then supports the corpus luteum. Its levels are also suppressed during pregnancy and it is not involved in parturition.

Visual 1: Flowchart - Depicting the hormonal cascade at the onset of labor. The chart can show how rising fetal cortisol leads to increased maternal estrogen, which in turn stimulates prostaglandins and oxytocin receptors, resulting in cervical ripening and uterine contractions.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of labor and cervical dilatation as background academic context rather than a clinical decision trigger.
Understanding this hormonal pathway is the basis for modern labor induction methods. For a woman with an 'unripe' or unfavorable cervix, synthetic prostaglandins (like Dinoprostone or Misoprostol) are administered to mimic the natural cervical ripening process initiated by estrogen.
This knowledge helps nurses anticipate the effectiveness of interventions. For example, starting an oxytocin infusion without first ensuring the cervix is ripe may lead to a long, ineffective, and painful induction.
What if? If a patient at term has ruptured membranes but is not having contractions and the cervix is firm and closed, the care team would likely administer a prostaglandin agent to ripen the cervix before starting oxytocin. This mimics the natural sequence and increases the chance of a successful vaginal delivery.

How to Approach the Question

First, identify the core of the question: it asks for the hormone responsible for cervical dilatation during labor.
Next, review the provided options and recall the primary function of each hormone in the context of the reproductive system.
Eliminate Testosterone immediately, as it is the primary male sex hormone.
Eliminate Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH), as their main roles are in regulating the menstrual cycle (follicular growth and ovulation, respectively) and they are not active in the labor process.
This leaves Estrogen as the only plausible option. Recall that at the end of pregnancy, estrogen levels rise, which helps to prepare the uterus and cervix for labor by increasing sensitivity to other hormones like oxytocin and stimulating prostaglandins.
Conclude that Estrogen is the best answer as it is the key hormonal initiator for the cascade of events leading to cervical dilatation.

Concept Tested & Keywords

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