Pregnancy and Lactation Physiology Practice Questions
40 free Pregnancy and Lactation Physiology practice questions for the Physiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
The hormone primarily responsible for maintenance of pregnancy in early gestation is:
- A Estrogen, secreted mainly by the placenta
- B Progesterone
- C Oxytocin, from the posterior pituitary
- D Prolactin, from the anterior pituitary
Correct answer: Progesterone
Progesterone maintains the endometrium and suppresses uterine contractions. In early pregnancy it is initially supported by corpus luteum secretion.
Human chorionic gonadotropin (hCG) is secreted mainly by the:
- A Corpus luteum
- B Placental trophoblasts
- C Maternal pituitary gland
- D Fetal adrenal gland
Correct answer: Placental trophoblasts
hCG is produced by syncytiotrophoblasts of the placenta. It maintains corpus luteum progesterone secretion in early pregnancy.
Which hormone is responsible for uterine growth during pregnancy?
- A Progesterone
- B Estrogen
- C Relaxin
- D Prolactin
Correct answer: Estrogen
Estrogen stimulates growth of the uterus and increases uterine blood flow. Its levels rise progressively during pregnancy.
The placenta gradually takes over progesterone production from the corpus luteum by approximately:
- A 4 weeks
- B 8 weeks
- C 12 weeks
- D 20 weeks
Correct answer: 12 weeks
By the end of the first trimester, the placenta becomes the major source of progesterone. This transition is known as the luteoplacental shift.
Relaxin during pregnancy primarily causes:
- A Stronger and more frequent uterine contractions
- B Cervical softening and pelvic ligament relaxation
- C Milk secretion
- D Complete suppression of ovarian estrogen synthesis
Correct answer: Cervical softening and pelvic ligament relaxation
Relaxin softens the cervix and relaxes pelvic ligaments. This facilitates parturition.
Which hormone is essential for milk synthesis in lactation?
- A Oxytocin
- B Prolactin
- C Estrogen
- D Progesterone
Correct answer: Prolactin
Prolactin stimulates synthesis of milk in mammary glands. Its secretion increases after delivery.
Milk ejection during breastfeeding is mediated by:
- A Prolactin
- B Estrogen
- C Oxytocin
- D Cortisol
Correct answer: Oxytocin
Oxytocin causes contraction of myoepithelial cells surrounding alveoli. This leads to milk let-down.
High levels of estrogen and progesterone during pregnancy prevent lactation by:
- A Suppressing prolactin secretion from the pituitary gland
- B Blocking prolactin action on breast tissue
- C Reducing the release of oxytocin from the pituitary
- D Physically inhibiting the developing milk ducts
Correct answer: Blocking prolactin action on breast tissue
Estrogen and progesterone inhibit the action of prolactin on mammary glands. Lactation begins after their levels fall post-delivery.
Which hormone increases maternal insulin resistance during pregnancy?
- A Insulin
- B Progesterone
- C Placental lactogen
- D Oxytocin, from the posterior pituitary
Correct answer: Placental lactogen
Human placental lactogen antagonizes insulin action. This ensures adequate glucose availability for the fetus.
The primary source of estrogen during pregnancy is:
- A The maternal ovary throughout gestation
- B The maternal adrenal gland
- C Placenta using fetal precursors
- D The developing fetal pituitary gland
Correct answer: Placenta using fetal precursors
The placenta synthesizes estrogen from androgen precursors supplied by the fetal adrenal gland. This requires fetoplacental cooperation.
Which physiological change commonly occurs in pregnancy?
- A Decreased blood volume
- B Decreased cardiac output
- C Increased blood volume
- D Reduced glomerular filtration rate
Correct answer: Increased blood volume
Blood volume increases to support placental circulation and fetal growth. This helps meet increased metabolic demands.
Gestational diabetes primarily results from:
- A Autoimmune destruction of pancreatic beta cells
- B Placental hormone-induced insulin resistance
- C Excessive insulin secretion by the pancreas
- D Markedly reduced glucose utilization by the fetus
Correct answer: Placental hormone-induced insulin resistance
Placental hormones such as human placental lactogen increase insulin resistance. This can lead to gestational diabetes.
Which hormone initiates labor by increasing uterine contractility near term?
- A Progesterone
- B Estrogen
- C Oxytocin
- D Prolactin
Correct answer: Oxytocin
Oxytocin stimulates uterine contractions. Its effect is enhanced by increased oxytocin receptor expression near term.
Progesterone during pregnancy helps prevent preterm labor by:
- A Stimulating the release of oxytocin near term
- B Reducing uterine muscle excitability
- C Increasing prostaglandin synthesis in the myometrium
- D Strongly enhancing the action of estrogen
Correct answer: Reducing uterine muscle excitability
Progesterone reduces myometrial excitability and suppresses contractions. This maintains uterine quiescence.
Which hormone increases breast ductal growth during pregnancy?
- A Progesterone
- B Estrogen
- C Oxytocin
- D Prolactin
Correct answer: Estrogen
Estrogen stimulates growth and branching of mammary ducts. This prepares the breast for lactation.
Colostrum differs from mature milk primarily by having higher levels of:
- A Fat
- B Lactose
- C Immunoglobulins
- D Water content
Correct answer: Immunoglobulins
Colostrum is rich in immunoglobulins, especially IgA. It provides passive immunity to the newborn.
Suckling stimulates prolactin secretion via:
- A A rise in hypothalamic dopamine release
- B Reduced hypothalamic dopamine inhibition
- C A sharp increase in estrogen secretion
- D Direct mechanical stimulation of the pituitary
Correct answer: Reduced hypothalamic dopamine inhibition
Suckling reduces dopamine release from the hypothalamus. This removes inhibition on prolactin secretion.
Which hormone suppresses ovulation during lactation?
- A Oxytocin
- B Prolactin
- C Estrogen
- D Progesterone
Correct answer: Prolactin
Prolactin suppresses GnRH secretion. This reduces gonadotropin release and inhibits ovulation.
The fetal adrenal gland contributes to pregnancy by:
- A Directly producing progesterone for the placenta
- B Producing mature estrogen and secreting it directly
- C Supplying androgen precursors for placental estrogen
- D Stimulating uterine contractions before term
Correct answer: Supplying androgen precursors for placental estrogen
The fetal adrenal produces androgens such as DHEA-S. These are converted to estrogen by the placenta.
Which change facilitates calcium supply to the fetus during pregnancy?
- A A fall in maternal active vitamin D levels
- B Increased intestinal calcium absorption
- C Reduced secretion of parathyroid hormone by the glands
- D A decrease in maternal bone turnover
Correct answer: Increased intestinal calcium absorption
Maternal intestinal calcium absorption increases due to elevated vitamin D activity. This supports fetal skeletal development.
Which placental hormone is primarily responsible for the 'diabetogenic' effect of pregnancy by decreasing maternal insulin sensitivity?
- A Human chorionic gonadotropin (hCG)
- B Human placental lactogen (hPL)
- C Estriol
- D Progesterone
Correct answer: Human placental lactogen (hPL)
Human placental lactogen (hPL), also known as human chorionic somatomammotropin, increases maternal insulin resistance to ensure a steady supply of glucose for the fetus.
What is the primary role of Human Chorionic Gonadotropin (hCG) during the first trimester of pregnancy?
- A To stimulate maturation of the fetal lungs
- B To maintain the corpus luteum for progesterone production
- C To directly initiate the process of parturition at term
- D To significantly increase the maternal basal metabolic rate
Correct answer: To maintain the corpus luteum for progesterone production
hCG rescues the corpus luteum from degeneration, ensuring continued progesterone and estrogen secretion until the placenta can take over around week 8-12.
During pregnancy, maternal blood volume increases significantly. Which of the following best describes the resulting 'physiological anemia'?
- A A true decrease in the total maternal red blood cell count
- B A failure of the bone marrow to produce enough hemoglobin
- C Plasma volume increasing more than the red blood cell mass
- D Iron deficiency anemia caused by excessive fetal iron absorption
Correct answer: Plasma volume increasing more than the red blood cell mass
Plasma volume increases by approximately 50%, while red cell mass increases by only 20-30%, leading to a hemodilution effect and a lower hematocrit.
Which hormone, produced by the placenta and the corpus luteum, softens the pelvic ligaments and helps dilate the cervix near term?
- A Oxytocin
- B Relaxin
- C Prolactin
- D Inhibin
Correct answer: Relaxin
Relaxin increases the flexibility of the pubic symphysis and helps soften the cervix, facilitating the passage of the fetus through the birth canal.
The 'fetal-placental unit' is required for the synthesis of Estriol because the placenta lacks which enzyme?
- A Aromatase
- B 17α-hydroxylase
- C 5α-reductase
- D Cholesterol desmolase
Correct answer: 17α-hydroxylase
The placenta cannot convert progesterone to androgens; it relies on the fetal adrenal glands to provide DHEA-S, which the placenta then converts into estriol.
Why does significant milk secretion NOT occur during pregnancy despite high prolactin levels?
- A The mammary alveolar tissue has not yet fully developed the capacity for milk synthesis
- B High levels of estrogen and progesterone inhibit the action of prolactin on the breast.
- C Oxytocin levels remain far too low throughout gestation to trigger the milk ejection reflex
- D The anterior pituitary gland is only able to release prolactin after placental delivery
Correct answer: High levels of estrogen and progesterone inhibit the action of prolactin on the breast.
While estrogen and progesterone stimulate breast development, they also competitively inhibit the lactogenic effect of prolactin on the mammary alveolar cells.
Which hormone is responsible for the 'milk ejection reflex' by causing contraction of myoepithelial cells?
- A Prolactin
- B Estrogen
- C Oxytocin
- D Dopamine
Correct answer: Oxytocin
Oxytocin, released from the posterior pituitary in response to suckling, causes the contraction of myoepithelial cells surrounding the alveoli, forcing milk into the ducts.
During lactation, high levels of prolactin suppress the reproductive cycle primarily by inhibiting the release of:
- A Gonadotropin-releasing hormone (GnRH) from the hypothalamus
- B Thyroid-stimulating hormone (TSH) from the anterior pituitary
- C Oxytocin from the posterior pituitary gland
- D Aldosterone from the adrenal cortex zona glomerulosa
Correct answer: Gonadotropin-releasing hormone (GnRH) from the hypothalamus
Prolactin inhibits the pulsatile release of GnRH from the hypothalamus, which in turn reduces FSH and LH levels, often leading to lactational amenorrhea.
Which component of colostrum provides the newborn with essential passive immunity?
- A Casein
- B Lactose
- C Secretory IgA
- D Triglycerides
Correct answer: Secretory IgA
Colostrum is rich in antibodies, particularly Secretory IgA, which protects the infant's gastrointestinal tract from pathogens.
Which cardiovascular change is typical during a normal pregnancy?
- A A modest reduction in resting maternal cardiac output near term
- B A marked increase in total systemic vascular resistance throughout gestation
- C Increased cardiac output and decreased systemic vascular resistance
- D A modest decrease in resting maternal heart rate throughout gestation
Correct answer: Increased cardiac output and decreased systemic vascular resistance
Cardiac output increases by 30-50% to meet fetal demands, while systemic vascular resistance decreases due to the vasodilatory effects of progesterone.
The onset of labor (parturition) is associated with an increase in the ratio of which two hormones?
- A hCG to hPL
- B Estrogen to Progesterone
- C Prolactin to Oxytocin
- D Aldosterone to Cortisol
Correct answer: Estrogen to Progesterone
An increasing estrogen-to-progesterone ratio near term increases the number of oxytocin receptors and gap junctions in the myometrium, promoting uterine excitability.
Which hormone is the primary stimulus for the growth and branching of the lactiferous ducts during puberty and pregnancy?
- A Progesterone
- B Oxytocin
- C Insulin
- D Estrogen
Correct answer: Estrogen
Estrogen is primarily responsible for ductal development, while progesterone is responsible for the growth of the alveolar-lobular structures.
What is the primary function of the 'progesterone plug' (mucus plug) in the cervix during pregnancy?
- A To mechanically prevent the entry of sperm into the uterus
- B To lubricate the birth canal during delivery
- C To store oxytocin in reserve for labor
- D To protect the uterus from ascending infections
Correct answer: To protect the uterus from ascending infections
Under the influence of progesterone, cervical mucus becomes thick and acidic, forming a physical and chemical barrier against bacteria.
Which respiratory change is commonly observed in the third trimester of pregnancy?
- A A decrease in resting tidal volume during the third trimester
- B An increase in the functional residual capacity of the maternal lungs
- C Increased minute ventilation and slight respiratory alkalosis
- D A decrease in the maternal respiratory rate during the third trimester
Correct answer: Increased minute ventilation and slight respiratory alkalosis
Progesterone stimulates the respiratory center to increase tidal volume, leading to hyperventilation (increased minute ventilation) and a lower maternal arterial PCO2.
Which renal adjustment occurs during pregnancy to handle increased waste products?
- A Decreased Glomerular Filtration Rate (GFR)
- B Decreased renal plasma flow
- C Increased glucose reabsorption threshold
- D Increased Glomerular Filtration Rate (GFR)
Correct answer: Increased Glomerular Filtration Rate (GFR)
GFR increases by nearly 50% during pregnancy due to increased cardiac output and renal vasodilation, often leading to lower serum creatinine levels.
Suckling-induced inhibition of which hypothalamic neurotransmitter leads to increased prolactin secretion?
- A Serotonin release from the raphe nuclei
- B Acetylcholine release from cholinergic neurons
- C Dopamine release from the arcuate nucleus neurons
- D Norepinephrine release from the locus coeruleus
Correct answer: Dopamine release from the arcuate nucleus neurons
Dopamine acts as a prolactin-inhibiting factor. Suckling inhibits dopamine release, thereby disinhibiting the lactotrophs in the anterior pituitary to secrete prolactin.
The placenta produces which hormone to stimulate the maternal thyroid gland, similar to TSH?
- A Human chorionic gonadotropin (hCG)
- B Corticotropin-releasing hormone (CRH)
- C Estriol
- D Progesterone
Correct answer: Human chorionic gonadotropin (hCG)
hCG has structural similarity to TSH and can weakly bind to TSH receptors, often causing a slight increase in free T4 and a transient decrease in TSH during the first trimester.
What happens to maternal calcium metabolism during pregnancy to support fetal skeletal development?
- A Maternal bone density steadily and permanently increases throughout gestation
- B Parathyroid hormone secretion is permanently and completely suppressed
- C Maternal urinary calcium excretion decreases steadily to zero
- D Intestinal calcium absorption increases due to elevated 1,25-dihydroxyvitamin D
Correct answer: Intestinal calcium absorption increases due to elevated 1,25-dihydroxyvitamin D
Estrogen and placental lactogen stimulate the production of active Vitamin D, which doubles maternal calcium absorption to meet the fetal demand without depleting maternal bone.
Which of the following is the primary androgen precursor used by the placenta to synthesize Estrogens?
- A Testosterone secreted directly by the fetal testes into circulation
- B Androstenedione secreted by the maternal adrenal cortex
- C Cortisol secreted directly by the fetal adrenal gland
- D Dehydroepiandrosterone sulfate (DHEA-S) from the fetal adrenal gland
Correct answer: Dehydroepiandrosterone sulfate (DHEA-S) from the fetal adrenal gland
The placenta lacks the enzymes to make androgens from scratch; it converts DHEA-S (mostly from the fetal adrenal glands) into estrogens like estradiol and estriol.
After delivery of the placenta, what is the primary trigger for the initiation of 'lactogenesis II' (copious milk production)?
- A A sudden drop in estrogen and progesterone
- B A sudden rise in circulating oxytocin levels
- C An increase in maternal growth hormone secretion
- D The occurrence of the infant's first cry
Correct answer: A sudden drop in estrogen and progesterone
The loss of the placenta causes a precipitous drop in estrogen and progesterone, which removes the inhibition on the breasts and allows prolactin to initiate full milk production.