Physiology of Pregnancy — MCQs

10 questions

What is the typical time between fertilization and implantation?

All are true about uteroplacental circulation except:

A patient with juvenile myoclonic epilepsy on valproate comes to you at 5 months of pregnancy with a normal level II scan. What will you advise?

Which of the following are advantages of state of haemodilution during pregnancy? 1. Optimum gaseous exchange between maternal and foetal circulation due to decreased blood viscosity 2. Protection against adverse effect of blood loss during delivery 3. Increased oxygen carrying capacity of blood Select the correct answer using the code given below.

Milk production in pregnancy is inhibited by :

What physiological event occurs during ovulation?

Where does meiosis occur in human females?

Disruption of the hypothalamic-pituitary portal system will lead to

Hyaline membrane disease of the lungs is characterized by –

Q10

The baseline oxyhemoglobin dissociation curve is depicted in blue color. Shift of curve to which side indicates Bohr effect?

Physiology of Pregnancy Indian Medical PG Practice Questions and MCQs

Question 1: What is the typical time between fertilization and implantation?

A. 2 days
B. 8 days (Correct Answer)
C. 14 days
D. 16 days

Explanation: ***8 days*** - **Fertilization** typically occurs in the **fallopian tube**, and the resulting **zygote** then undergoes several cell divisions while migrating towards the uterus. - Implantation, the process by which the **blastocyst embeds into the uterine wall**, usually begins around day 6 post-fertilization and is completed by day 8-10. *2 days* - At 2 days post-fertilization, the embryo is typically in the **2-cell to 4-cell stage** and is still located within the fallopian tube, far from the implantation site. - This stage is too early for implantation to occur, as the embryo has not yet reached the **blastocyst stage** or the uterus. *14 days* - By 14 days post-fertilization, implantation would have long been completed, and the initial stages of **trophoblast development** and formation of the **placenta** would be underway. - This time frame represents a more advanced stage of pregnancy, whereas implantation is an early event. *16 days* - Sixteen days post-fertilization is well past the window for initial implantation; at this point, significant embryonic development has occurred, and the woman might even be experiencing early signs of **pregnancy**, such as a missed period. - Implantation is a much earlier process, concluding by day 10 at the latest.

Question 2: All are true about uteroplacental circulation except:

A. The villi depend on the maternal blood for their nutrition
B. Blood in the intervillous space is completely replaced 3-4 times per minute
C. A mature placenta has 150 ml of blood in the villi system and 350 ml of blood in the intervillous space (Correct Answer)
D. Intervillous blood flow at term is 500-600 ml per minute

Explanation: ***A mature placenta has 150 ml of blood in the villi system and 350 ml of blood in the intervillous space*** - This statement is incorrect because a **mature placenta** typically holds approximately **350 ml of blood** in the **villi system** and **150 ml of blood** in the **intervillous space**, which is the reverse of what is stated. - The villi system contains the fetal blood, which has a larger volume within the placental unit. *Blood in the intervillous space is completely replaced 3-4 times per minute* - This is a correct statement regarding uteroplacental circulation, as the **high turnover rate** ensures efficient **nutrient and gas exchange** between mother and fetus. - The rapid replacement prevents stagnant blood and facilitates continuous delivery of essential substances. *The villi depend on the maternal blood for their nutrition* - This statement is true because the **chorionic villi**, which are the functional units of the placenta, are bathed in **maternal blood** within the intervillous space. - The placental tissue itself receives its **nutrients and oxygen** directly from this maternal blood supply. *Intervillous blood flow at term is 500-600 ml per minute* - This is an accurate physiological fact. At term, the **maternal blood flow** through the intervillous space is indeed substantial, typically ranging from **500 to 700 ml per minute**, ensuring adequate perfusion for the growing fetus. - This significant blood flow is crucial for meeting the high metabolic demands of the fetus.

Question 3: A patient with juvenile myoclonic epilepsy on valproate comes to you at 5 months of pregnancy with a normal level II scan. What will you advise?

A. Increase the dose of the drug
B. Change the drug
C. Decrease the dose of the drug
D. Continue the drug in the same dose (Correct Answer)

Explanation: ***Continue the drug in the same dose*** - As the patient is already at **5 months of pregnancy** with a **normal level II scan**, the risk of major congenital malformations has largely passed. - **Maintaining seizure control** is crucial during pregnancy, as uncontrolled seizures pose significant risks to both the mother and fetus. *Change the drug* - Changing an antiepileptic drug during pregnancy, especially in the second trimester, can lead to a **loss of seizure control** and potentially expose the fetus to a new drug with unknown risks. - The period of highest risk for **major congenital malformations** from valproate exposure is during the first trimester. *Decrease the dose of the drug* - Decreasing the dose of valproate could lead to **breakthrough seizures**, which are dangerous for both the mother and the fetus. - **Plasma drug levels** often decrease in pregnancy due to increased volume of distribution and metabolism, potentially requiring a stable or even increased dose to maintain therapeutic levels. *Increase the dose of the drug* - Increasing the dose without clear clinical indication (e.g., breakthrough seizures or subtherapeutic levels) could increase the risk of **dose-dependent side effects** for both mother and fetus. - While therapeutic drug monitoring for valproate is often done in pregnancy, a **normal level II scan** does not automatically warrant a dose increase.

Question 4: Which of the following are advantages of state of haemodilution during pregnancy? 1. Optimum gaseous exchange between maternal and foetal circulation due to decreased blood viscosity 2. Protection against adverse effect of blood loss during delivery 3. Increased oxygen carrying capacity of blood Select the correct answer using the code given below.

A. 1, 2 and 3
B. 1 and 3 only
C. 2 and 3 only
D. 1 and 2 only (Correct Answer)

Explanation: ***1 and 2 only*** - **Haemodilution** during pregnancy, characterized by a disproportionate increase in plasma volume relative to red blood cell mass, leads to decreased blood **viscosity**. - A lower blood viscosity facilitates more efficient **gaseous exchange** (oxygen and carbon dioxide) between the maternal and fetal circulations at the placenta, and also offers a degree of protection against the effects of **blood loss during delivery** by maintaining circulating volume. *1, 2 and 3* - While haemodilution promotes efficient gaseous exchange and protects against blood loss, it does **not increase the oxygen carrying capacity** of the blood. - In fact, the relative decrease in red blood cell concentration leads to physiological anemia of pregnancy, which reduces the oxygen-carrying capacity (though total oxygen delivery may be maintained by increased cardiac output). *2 and 3 only* - This option correctly identifies protection against blood loss but incorrectly states an **increased oxygen carrying capacity**. - The primary mechanism for improved oxygen delivery is enhanced blood flow due to reduced viscosity and increased cardiac output, not an increased concentration of oxygen carriers. *1 and 3 only* - This option correctly identifies improved gaseous exchange but incorrectly suggests an **increased oxygen carrying capacity**. - Protection against blood loss is a significant benefit of pregnancy-induced haemodilution, which is overlooked in this choice.

Question 5: Milk production in pregnancy is inhibited by :

A. Low luteinizing hormone
B. Low thyroid-stimulating hormone
C. High estrogen (Correct Answer)
D. Human somatomammotropin

Explanation: ***High estrogen*** - High levels of **estrogen** and progesterone during pregnancy inhibit milk production by blocking the action of **prolactin** on the mammary glands. - After delivery, the sudden drop in these hormones removes the inhibition, allowing prolactin to stimulate **lactogenesis**. *Low luteinizing hormone* - **Luteinizing hormone (LH)** is primarily involved in ovulation and corpus luteum formation, not directly in the inhibition of milk production. - Low LH levels would impact fertility but not have a direct inhibitory effect on lactation. *Low thyroid-stimulating hormone* - **Thyroid-stimulating hormone (TSH)** regulates thyroid function, which can indirectly affect metabolism and overall well-being. - While **hypothyroidism** can impact milk supply, low TSH itself is not a direct inhibitor of milk production. *Human somatomammotropin* - **Human placental lactogen (HPL)**, also known as human chorion somatomammotropin, is produced by the placenta. - It promotes mammary gland development and has weak lactogenic properties but does not inhibit milk production.

Question 6: What physiological event occurs during ovulation?

A. Inhibin A levels increase.
B. FSH increases steroid synthesis in granulosa cells. (Correct Answer)
C. Activin enhances FSH action on granulosa cells.
D. Completion of the first meiotic division of the oocyte occurs just before ovulation.

Explanation: ***FSH increases steroid synthesis in granulosa cells.*** - During the **periovulatory period**, FSH continues to support **estrogen synthesis** in granulosa cells of the dominant follicle. - While FSH levels peak in the **mid-follicular phase**, FSH (along with the LH surge) maintains steroidogenic activity through ovulation. - Among the given options, this represents the most relevant ongoing physiological process during ovulation, though the primary event is follicular rupture and oocyte release. *Completion of the first meiotic division of the oocyte occurs just before ovulation.* - The **LH surge** triggers completion of **meiosis I** approximately **36-38 hours before ovulation**, forming a secondary oocyte and first polar body. - This event occurs **prior to** ovulation, not during it. At ovulation, the **secondary oocyte** (arrested in **metaphase II**) is released. - Meiosis II is only completed if **fertilization** occurs. *Inhibin A levels increase.* - **Inhibin A** levels rise significantly **after ovulation** during the **luteal phase**, produced by the corpus luteum. - Around ovulation, **inhibin B** is more prominent, while inhibin A remains relatively low. *Activin enhances FSH action on granulosa cells.* - **Activin** enhances FSH action throughout the **follicular phase**, promoting follicular growth and estrogen production. - This is a continuous regulatory mechanism, not a specific event occurring during ovulation itself.

Question 7: Where does meiosis occur in human females?

A. In the adult ovary (Correct Answer)
B. At birth in the ovary
C. In the adult testis
D. In the prepubertal testis

Explanation: ***In the adult ovary*** - **Meiosis I** in oocytes starts during fetal development but arrests in prophase I. It resumes and completes in the **adult ovary** just before ovulation in response to hormonal signals. - **Meiosis II** begins after the completion of Meiosis I and arrests in metaphase II. It is only completed upon **fertilization** by a sperm, also occurring within the adult reproductive tract. *At birth in the ovary* - At birth, female ovaries contain primary oocytes that have entered **meiosis I** but are arrested in prophase I; actual meiotic divisions promoting maturation do not occur at this stage. - The completion of meiosis I and the initiation of meiosis II are processes that are **post-puberty** and occur in response to hormonal changes leading to ovulation. *In the adult testis* - The testis is the male gonad, and it is the site of **spermatogenesis**, the process of sperm production involving meiosis in males. - **Oogenesis**, the formation of female gametes, occurs exclusively in the **ovaries** of females. *In the prepubertal testis* - In the prepubertal testis, spermatogenesis has not yet begun, and thus **meiosis does not occur** at this stage in males. - Meiosis in males usually begins during **puberty** under the influence of hormones like testosterone.

Question 8: Disruption of the hypothalamic-pituitary portal system will lead to

A. Increased follicular development due to elevated circulating levels of PRL.
B. Ovulation with subsequent increase in circulating progesterone levels.
C. Increased FSH levels due to reduced ovarian inhibin levels.
D. High circulating levels of PRL, low levels of LH and FSH, leading to ovarian atrophy. (Correct Answer)

Explanation: ***High circulating levels of PRL, low levels of LH and FSH, leading to ovarian atrophy.*** - Disruption of the **hypothalamic-pituitary portal system** impairs the transport of **gonadotropin-releasing hormone (GnRH)** to the anterior pituitary, leading to decreased **luteinizing hormone (LH)** and **follicle-stimulating hormone (FSH)**. - This disruption also prevents **dopamine** from reaching the anterior pituitary, leading to uncontrolled **prolactin (PRL)** secretion (disinhibition), which suppresses GnRH and **gonadotropin** release, contributing to **ovarian atrophy**. *Increased follicular development due to elevated circulating levels of PRL.* - Elevated **prolactin (PRL)** levels typically **inhibit** ovarian function and **suppress follicular development**, rather than promoting it. - **Hyperprolactinemia** causes **hypogonadism** by interfering with **GnRH** pulsatility and directly affecting ovarian responsiveness to **gonadotropins**. *Ovulation with subsequent increase in circulating progesterone levels.* - Disruption of the portal system leads to decreased **LH** and **FSH**, which are essential for **follicular development** and **ovulation**. - Without ovulation, a **corpus luteum** cannot form, and therefore, there will be no significant increase in **progesterone** levels. *Increased FSH levels due to reduced ovarian inhibin levels.* - Reduced **FSH** and **LH** levels, resulting from the disruption, would lead to impaired **follicular development** and thus **reduced estrogen** and **inhibin** production by the ovaries. - While reduced inhibin usually leads to increased FSH (negative feedback), the primary impairment in this scenario is at the **hypothalamic-pituitary axis**, directly causing low **gonadotropin** levels, overriding the inhibin effect.

Question 9: Hyaline membrane disease of the lungs is characterized by –

A. FRC is reduced compared to closing volume (Correct Answer)
B. FRC is increased compared to closing volume
C. FRC is equal to closing volume
D. FRC is not related to closing volume

Explanation: ***FRC is reduced compared to closing volume*** - In **Hyaline Membrane Disease (HMD)**, severe **surfactant deficiency** leads to widespread **atelectasis** and a significant reduction in **functional residual capacity (FRC)**. - Due to the collapse of alveoli and small airways, the **closing volume (CV)**, which is the lung volume at which small airways begin to close, becomes relatively larger than the already reduced FRC. *FRC is increased compared to closing volume* - This statement is incorrect because HMD is characterized by diffuse **atelectasis**, which drastically reduces **FRC**. - An increased FRC relative to closing volume would imply better lung compliance and less small airway closure, contrary to the pathology of HMD. *FRC is equal to closing volume* - This scenario would represent a critical point where extensive airway closure occurs, but in HMD, the **FRC is significantly lower** than the critical closing volume due to severe **surfactant deficiency** and widespread collapse. - While there is considerable airway closure, the FRC is typically *below* the closing volume, leading to shunt and severe hypoxemia. *FRC is not related to closing volume* - This is incorrect because FRC and closing volume are intimately related in lung mechanics, especially in conditions like HMD. - **Closing volume** reflects the point at which airways begin to collapse, and in disease states like HMD, the interplay between a reduced FRC and an elevated closing volume explains the severe gas exchange abnormalities.

Question 10: The baseline oxyhemoglobin dissociation curve is depicted in blue color. Shift of curve to which side indicates Bohr effect?

A. Green (shift to left)
B. Red (shift to right) (Correct Answer)
C. Blue (no shift)
D. None of these

Explanation: ***Red (shift to right)*** - The **Bohr effect** describes the rightward shift of the oxyhemoglobin dissociation curve caused by increased **CO2** and decreased **pH** (acidosis). - This rightward shift indicates **decreased oxygen affinity**, allowing hemoglobin to release oxygen more readily to metabolically active tissues that produce CO2 and acid. - This is represented by the **red curve** in the image. *Green (shift to left)* - A **left shift** indicates **increased oxygen affinity**, meaning hemoglobin holds onto oxygen more tightly and releases it less readily. - This occurs with **decreased CO2**, **increased pH** (alkalosis), **decreased temperature**, and **decreased 2,3-BPG**. - These are **opposite conditions** to the Bohr effect. *Blue (no shift)* - The **blue curve** represents the baseline oxyhemoglobin dissociation curve with no shift. - The Bohr effect specifically refers to a **curve shift** (rightward with increased CO2/decreased pH), not the baseline position. - Therefore, blue does not represent the Bohr effect. *None of these* - The **red curve** (rightward shift) accurately represents the Bohr effect, making this option incorrect. - The Bohr effect is a well-established concept with a **characteristic rightward shift** when CO2 increases or pH decreases.

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