Hormonal Regulation of Labor — MCQs
Which of the following options include cardinal movements that occur during labor?
Oxytocin causes all EXCEPT:
Which method is most appropriate for cervical ripening in a term pregnancy with oligohydramnios and reactive NST?
True about oxytocin are all except
Which of the following drugs used for management of preterm labor also has neuroprotective role in fetus:
Female with 41 wk gestation confirmed by radiological investigation, very sure of her LMP, no uterine contractions, no effacement and no dilatation. What should be done to induce labor?
Decidual reaction is due to which hormone?
Which of the following statements about the contraction stress test (CST) is MOST accurate?
A primigravida at 38 weeks of gestation has gone into labor. Oxytocin was started to augment labor. The second messenger system through which oxytocin acts is:
Beta-hCG is secreted by:
Hormonal Regulation of Labor Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following options include cardinal movements that occur during labor?
- A. Engagement
- B. Descent, Flexion, Internal Rotation (Correct Answer)
- C. Shoulder Dystocia
- D. External Rotation
Explanation: ***Descent, Flexion, Internal Rotation*** - These are three of the **seven cardinal movements** of labor, which ensure the **optimal passage** of the fetus through the birth canal. - The seven cardinal movements are: **Engagement, Descent, Flexion, Internal Rotation, Extension, External Rotation (Restitution), and Expulsion**. - These movements occur sequentially or in combination, adapting the fetal head and body to the **pelvic diameters**. *Engagement* - While engagement is indeed a **cardinal movement** (the first one), the question asks which options include cardinal movements in a broader context. - Engagement alone refers to the **descent of the widest diameter** of the fetal presenting part to a level below the pelvic inlet. *Shoulder Dystocia* - **Shoulder dystocia** is a **complication of labor** where the anterior shoulder impacts behind the maternal pubic symphysis, NOT a cardinal movement. - It requires specific **obstetric maneuvers** to resolve and prevent fetal injury. *External Rotation* - **External rotation (restitution)** is indeed one of the cardinal movements, occurring after delivery of the head when it rotates to align with the shoulders. - However, in the context of this question, Option B provides a more comprehensive representation of multiple sequential cardinal movements.
Question 2: Oxytocin causes all EXCEPT:
- A. Milk ejection
- B. Milk production (Correct Answer)
- C. Induction of labour
- D. Stimulates myoepithelial cells
Explanation: ***Milk production*** - **Oxytocin** is primarily involved in the **milk ejection reflex** (let-down), but prolactin is the hormone responsible for **milk synthesis** or production. - While oxytocin facilitates the release of milk already produced, it does not stimulate the **mammary glands** to produce more milk. *Milk ejection* - Oxytocin causes contraction of the **myoepithelial cells** surrounding the alveoli in the mammary glands, leading to the **ejection of milk** into the ducts. - This reflex is crucial for **breastfeeding** and is often stimulated by the suckling of an infant. *Induction of labour* - **Oxytocin** stimulates rhythmic contractions of the **uterine smooth muscle**, making it a key hormone for initiating and progressing **labor**. - It is often administered exogenously to **induce** or augment labor due to its **uterotonic effects**. *Stimulates myoepithelial cells* - Oxytocin directly acts on the **myoepithelial cells** within the breast to cause their contraction. - This contraction generates pressure that forces milk from the **alveoli** into the **lactiferous ducts**, leading to milk ejection.
Question 3: Which method is most appropriate for cervical ripening in a term pregnancy with oligohydramnios and reactive NST?
- A. Dinoprostone gel 0.5mg
- B. Foley catheter (Correct Answer)
- C. Misoprostol 25mcg vaginal
- D. Oxytocin infusion
Explanation: **Foley catheter** - **Mechanical methods** like the Foley catheter are preferred for cervical ripening in the presence of **oligohydramnios** because they do not carry the risk of inducing uterine hyperstimulation, which can further compromise fetal well-being. - The reactive non-stress test (NST) indicates the fetus is currently healthy, but oligohydramnios suggests a need to minimize any potential stress, making mechanical ripening a safer choice. *Dinoprostone gel 0.5mg* - **Prostaglandins** like dinoprostone can increase the risk of **uterine hyperstimulation**, which could be particularly dangerous for a fetus with oligohydramnios as it restricts blood flow and oxygen. - While effective for ripening, the risk profile is higher compared to mechanical methods when fetal compromise (like oligohydramnios) is present. *Misoprostol 25mcg vaginal* - **Misoprostol** is a potent prostaglandin analog that carries a significant risk of **uterine tachysystole** and hyperstimulation. - In cases with **oligohydramnios**, any drug-induced increase in uterine activity could further strain fetal oxygenation and well-being. *Oxytocin infusion* - **Oxytocin** is primarily used for **induction of labor** (to stimulate contractions) and not for cervical ripening directly. - Initiating oxytocin without a ripened cervix is less effective and carries a higher risk of failed induction and potentially C-section, and it does not address the need for cervical changes first.
Question 4: True about oxytocin are all except
- A. Causes contraction of upper segment
- B. Causes uterine contraction of body
- C. Secreted by posterior pituitary
- D. Synthesized by anterior pituitary (Correct Answer)
Explanation: ***Synthesized by anterior pituitary*** - Oxytocin is **synthesized in the hypothalamus** (specifically in the paraventricular and supraoptic nuclei), not in the anterior pituitary. - The **anterior pituitary** produces different hormones like **FSH, LH, ACTH, TSH, prolactin, and growth hormone**, but does not synthesize oxytocin. *Causes contraction of upper segment* - Oxytocin does cause **contractions of the upper uterine segment** as part of coordinated uterine activity during labor. - This contributes to **fundal dominance** where contractions are strongest at the fundus and weaken toward the cervix. *Causes uterine contraction of body* - Oxytocin stimulates **rhythmic contractions of the myometrium** throughout the uterine body during labor. - These **coordinated contractions** are essential for effective cervical dilation and fetal expulsion. *Secreted by posterior pituitary* - Oxytocin is indeed **stored and released by the posterior pituitary** after being transported from the hypothalamus. - The posterior pituitary acts as a **storage and release site** for both oxytocin and **antidiuretic hormone (ADH)**.
Question 5: Which of the following drugs used for management of preterm labor also has neuroprotective role in fetus:
- A. Ritodrine
- B. MgSO4 (Correct Answer)
- C. Nifedipine
- D. Isoxsuprine
Explanation: ***MgSO4*** - **Magnesium sulfate (MgSO4)** is a commonly used tocolytic for preterm labor that also offers significant **neuroprotective benefits** for the fetus. - It reduces the risk and severity of **cerebral palsy** and other neurological morbidities in preterm infants. *Ritodrine* - **Ritodrine** is a **beta-2 adrenergic agonist** that relaxes uterine smooth muscle, thereby inhibiting contractions. - It has no known neuroprotective effects on the fetus; its primary role is solely to **delay preterm labor**. *Nifedipine* - **Nifedipine** is a **calcium channel blocker** that inhibits the entry of calcium into uterine smooth muscle cells, reducing contractions. - While effective as a tocolytic, it does not confer specific neuroprotective benefits to the fetus. *Isoxsuprine* - **Isoxsuprine** is a **beta-adrenergic agonist** that, similar to ritodrine, acts by relaxing uterine musculature. - It is used for tocolysis but lacks any documented neuroprotective properties for the developing fetus.
Question 6: Female with 41 wk gestation confirmed by radiological investigation, very sure of her LMP, no uterine contractions, no effacement and no dilatation. What should be done to induce labor?
- A. PGE1 tab (Correct Answer)
- B. PGE2 gel
- C. PGF2alpha
- D. Intracervical foley’s
Explanation: ***PGE1 tab*** - **Misoprostol (PGE1)** is an effective agent for **cervical ripening** and labor induction in cases of an unfavorable cervix (no effacement, no dilatation). - It is cost-effective, stable at room temperature, and widely used in resource-limited settings. - Can be administered orally or vaginally with good efficacy for cervical ripening at term. - In this post-term pregnancy with unfavorable cervix, pharmacological ripening is appropriate. *PGE2 gel* - **PGE2 (dinoprostone)** gel or cervical insert is also an effective option for cervical ripening. - Both PGE1 and PGE2 are acceptable first-line agents; the choice may depend on availability, cost, and institutional protocols. - PGE2 formulations are FDA-approved and widely used, though may be more expensive than misoprostol. *PGF2alpha* - **PGF2alpha (carboprost)** is primarily used for the **management of postpartum hemorrhage** due to its potent myometrial contracting effect. - It is **not indicated** for induction of labor at term as its strong uterine contractions can cause excessive uterine stimulation and fetal distress. *Intracervical foley's* - An **intracervical Foley catheter** is a mechanical method that causes cervical ripening through direct pressure and stimulation of local prostaglandin release. - It is an evidence-based alternative with lower risk of uterine hyperstimulation compared to pharmacological methods. - Both mechanical and pharmacological methods are acceptable first-line options for cervical ripening in post-term pregnancy with unfavorable cervix.
Question 7: Decidual reaction is due to which hormone?
- A. Progesterone (Correct Answer)
- B. Estrogen
- C. LH
- D. FSH
Explanation: ***Progesterone*** - The **decidual reaction** is a specific uterine stromal cell differentiation process that prepares the endometrium for **implantation and pregnancy maintenance**. - This process is primarily induced and maintained by **progesterone**, which causes stromal cells to enlarge, accumulate glycogen and lipids, and secrete various factors essential for embryonic development. *Estrogen* - Estrogen plays a crucial role in the **proliferation of the endometrium** during the follicular phase, building up the uterine lining. - While estrogen is essential, it acts in conjunction with progesterone; progesterone is the **primary hormone** responsible for the decidualization process itself. *LH* - Luteinizing hormone (LH) is responsible for triggering **ovulation** and stimulating the corpus luteum to produce progesterone. - LH's direct role is not in the decidual reaction of the endometrium but rather in the **ovarian events** that lead to the production of the hormones that cause decidualization. *FSH* - Follicle-stimulating hormone (FSH) is vital for the growth and maturation of **ovarian follicles** and **estrogen production**. - FSH does not directly induce the decidual reaction but facilitates the production of estrogen, which then contributes to endometrial proliferation, a precursor to progesterone's decidualizing effect.
Question 8: Which of the following statements about the contraction stress test (CST) is MOST accurate?
- A. Invasive method
- B. Detects fetal well being
- C. Negative test is associated with good fetal outcome (Correct Answer)
- D. Oxytocin is never used in the test
Explanation: ***Negative test is associated with good fetal outcome*** - A **negative CST** indicates that there are no late or significant variable decelerations in response to uterine contractions, suggesting the fetus can tolerate labor. - This finding is strongly correlated with **fetal well-being** and a low likelihood of fetal distress in the near future, with a **negative predictive value of approximately 99%**. *Invasive method* - The CST is considered a **non-invasive test**, as it involves external monitoring of fetal heart rate and uterine contractions. - No instruments are inserted into the body, differentiating it from truly invasive procedures like **amniocentesis**. *Detects fetal well being* - While the CST provides valuable information, it specifically assesses **uteroplacental function and fetal oxygenation reserve** during the stress of contractions, rather than comprehensive fetal well-being. - It identifies fetuses at risk for **uteroplacental insufficiency** but does not evaluate other parameters of fetal health. - Other tests like the **biophysical profile** offer a more comprehensive assessment of fetal well-being, including parameters like fetal breathing, movement, tone, and amniotic fluid volume. *Oxytocin is never used in the test* - **Oxytocin** is frequently used to induce uterine contractions if spontaneous contractions are insufficient for the test (oxytocin challenge test or OCT). - Alternatively, **nipple stimulation** can be used to achieve adequate contractions for the CST.
Question 9: A primigravida at 38 weeks of gestation has gone into labor. Oxytocin was started to augment labor. The second messenger system through which oxytocin acts is:
- A. Tyrosine kinase
- B. Phospholipase C (IP3/DAG pathway) (Correct Answer)
- C. cGMP
- D. cAMP
Explanation: ***Phospholipase C (IP3/DAG pathway)*** - Oxytocin binds to its receptor, which is a **Gq protein-coupled receptor**. This activates **phospholipase C**. - **Phospholipase C** then hydrolyzes **phosphatidylinositol 4,5-bisphosphate (PIP2)** into **inositol triphosphate (IP3)** and **diacylglycerol (DAG)**, which act as second messengers to increase intracellular calcium and mediate myometrial contraction. *Tyrosine kinase* - **Tyrosine kinase receptors** are typically activated by growth factors (e.g., insulin, epidermal growth factor) and lead to phosphorylation cascades. - This mechanism is not primarily associated with the downstream signaling of **oxytocin receptors**. *cGMP* - **Cyclic guanosine monophosphate (cGMP)** is a second messenger primarily involved in signaling pathways initiated by **nitric oxide** and some peptide hormones. - It often acts to cause smooth muscle relaxation, which is contrary to oxytocin's role in uterine contraction. *cAMP* - **Cyclic adenosine monophosphate (cAMP)** is a common second messenger for many hormones that bind to **Gs protein-coupled receptors**. - Hormones such as **epinephrine (beta-adrenergic receptors)** and **glucagon** utilize cAMP, typically leading to different cellular responses than those of oxytocin.
Question 10: Beta-hCG is secreted by:
- A. Yolk sac
- B. Syncytiotrophoblast (Correct Answer)
- C. Liver
- D. Umbilical cord
Explanation: ***Syncytiotrophoblast*** - The **syncytiotrophoblast** is the outer layer of the trophoblast that surrounds the blastocyst and later the chorionic villi. - It is responsible for the secretion of various hormones, including **beta-hCG**, which is crucial for maintaining the corpus luteum and pregnancy. *Yolk sac* - The **yolk sac** is involved in early nutrient transfer, hematopoiesis, and germ cell formation. - It does not produce **beta-hCG**. *Liver* - The **liver** is a major organ of metabolism, detoxification, and protein synthesis. - It does not produce **beta-hCG**, which is specific to pregnancy. *Umbilical cord* - The **umbilical cord** connects the fetus to the placenta, facilitating nutrient and oxygen exchange. - It does not have endocrine functions and does not secrete **beta-hCG**.
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free