Anatomy and Physiology of Pregnancy: Fetal Development, Placenta, and Maternal Changes Practice Questions

25 multiple-choice questions on Anatomy and physiology of pregnancy: fetal development, placenta, and maternal changes for paramedic and EMT students, from Chapter 42 (Obstetrics). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. A woman at 30 weeks with type 1 diabetes has vomited all day and is breathing deeply. Her glucose is only 190 mg/dL. You should still suspect DKA because pregnancy:

   1. A. Raises the glucose level at which ketones begin to form
   2. B. Blocks ketone production until the glucose tops 400
   3. C. Lowers her bicarbonate, so acidosis comes sooner
   4. D. Makes deep, rapid breathing a normal finding at rest
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   Answer: C. Lowers her bicarbonate, so acidosis comes sooner

   The mild respiratory alkalosis of pregnancy is offset by lower serum bicarbonate, so a pregnant woman has less buffer and can develop DKA quickly at modest glucose levels, sometimes below 200 mg/dL. Pregnancy raises tidal volume, but deep Kussmaul breathing with vomiting is not normal and points to acidosis.

2. About how many days after fertilization does the blastocyst normally implant in the uterine wall?

   1. A. About 1 day
   2. B. About 7 days
   3. C. About 21 days
   4. D. About 40 days
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   Answer: B. About 7 days

   The fertilized egg divides as it moves down the fallopian tube and implants roughly a week later. Implantation within a day would mean it never left the tube, which is the setup for an ectopic pregnancy.

3. The developing human is called a fetus rather than an embryo beginning at about:

   1. A. 2 weeks after fertilization
   2. B. 20 weeks after fertilization
   3. C. The first fetal movement
   4. D. 8 weeks after fertilization
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   Answer: D. 8 weeks after fertilization

   The embryonic period, when the organ systems form, runs through about the eighth week after conception; from then on the term fetus is used. Twenty weeks is the threshold used for viability counts and parity, not for the name change.

4. Most organ systems form during the embryonic period, which ends at about 10 weeks of gestation. This matters clinically because it is when the developing baby is:

   1. A. Most vulnerable to drugs and toxins
   2. B. Least affected by maternal hypoxia
   3. C. Protected from most maternal viruses
   4. D. Large enough to be felt through the abdomen
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   Answer: A. Most vulnerable to drugs and toxins

   Organs form from about 3 to 8 weeks after fertilization (about 5 to 10 weeks of gestation), so this is when alcohol, some medications, and other teratogens do the most harm. The embryo is never protected from maternal hypoxia; it depends entirely on maternal oxygen delivery through the placenta. Many viruses, such as rubella, cytomegalovirus, and Zika, cross the placenta and cause malformations precisely in this period. The uterus does not rise out of the pelvis until about 12 weeks, so neither it nor the embryo can be felt abdominally this early. (Williams Obstetrics, embryogenesis; Caroline, fetal development.)

5. Pregnant women are more likely than other women to develop pyelonephritis from a simple bladder infection mainly because:

   1. A. Pregnancy hormones make the bladder lining much thicker
   2. B. The kidneys filter less blood during pregnancy
   3. C. Higher estrogen levels kill off the normal vaginal flora
   4. D. Progesterone and the uterus slow the flow of urine
   Show answer

   Answer: D. Progesterone and the uterus slow the flow of urine

   Progesterone relaxes the smooth muscle of the ureters, and the growing uterus presses on them, so urine stagnates and bacteria ascend more easily, especially on the right. The GFR actually rises in pregnancy, so reduced filtering is not the reason.

6. After a field delivery, you look at the cut end of the cord and count only two vessels instead of the usual three. This finding:

   1. A. Is the normal number of vessels
   2. B. Means the cord was clamped wrong
   3. C. May signal a congenital anomaly
   4. D. Shows that the infant is preterm
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   Answer: C. May signal a congenital anomaly

   A normal cord has two arteries and one vein; a single umbilical artery is linked to congenital kidney and heart anomalies, so report it to the receiving staff. It is not normal, and clamping technique does not change the number of vessels.

7. You need to insert an airway adjunct in a woman at 37 weeks who is postictal with snoring respirations. Compared with a nonpregnant patient, a nasopharyngeal airway is more likely to:

   1. A. Cause brisk bleeding from swollen nasal tissue
   2. B. Enter the cranial vault through the cribriform plate
   3. C. Trigger vomiting because of the gag reflex
   4. D. Be too short because the nasal passage is longer
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   Answer: A. Cause brisk bleeding from swollen nasal tissue

   Higher estrogen and blood volume make the nasal mucosa engorged and fragile in late pregnancy, so nasal airways, nasal tubes, and nasogastric tubes bleed easily and are best avoided or placed gently. Intracranial placement is a concern with basilar skull fracture, not pregnancy.

8. Before birth, most blood bypasses the fetal lungs because:

   1. A. The fetal lungs extract oxygen from fluid
   2. B. Fluid-filled lungs have high resistance
   3. C. Pulmonary vessels are dilated by low oxygen
   4. D. Systemic resistance is higher than pulmonary
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   Answer: B. Fluid-filled lungs have high resistance

   High pulmonary vascular resistance in the fluid-filled lungs diverts blood through the foramen ovale and ductus arteriosus. Low fetal oxygen levels constrict rather than dilate the pulmonary vessels, and the low-resistance placenta keeps systemic resistance below pulmonary resistance, which is why blood crosses the ductus from the pulmonary artery to the aorta. The fetal lungs do not oxygenate blood at all; the placenta does that job until birth.

9. A healthy woman at 36 weeks has a 12-lead ECG before an interfacility transfer. Because the enlarged uterus pushes the heart upward and to the left, a normal finding is:

   1. A. Marked right axis deviation, beyond +120
   2. B. A mild left shift of the electrical axis
   3. C. ST elevation in two contiguous leads
   4. D. A PR interval of more than 0.30 seconds
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   Answer: B. A mild left shift of the electrical axis

   The rising diaphragm displaces and rotates the heart, so a slight left shift of the QRS axis (about 15 degrees), sometimes with a small Q wave or T-wave inversion in lead III, is a normal ECG change in late pregnancy. Marked right axis deviation suggests right heart strain, for example from pulmonary embolism, which pregnancy makes more likely, so it must not be dismissed. ST elevation in contiguous leads is an infarction pattern; pregnancy-associated coronary dissection is a real cause and is treated as a STEMI. A PR interval over 0.30 seconds is first-degree heart block; pregnancy raises the heart rate and does not normally prolong the PR interval. (Williams Obstetrics, maternal physiology.)

10. Quickening, the first fetal movement the mother can feel, usually occurs at about:

    1. A. 6 to 8 weeks of gestation
    2. B. 28 to 32 weeks of gestation
    3. C. 36 to 38 weeks of gestation
    4. D. 16 to 20 weeks of gestation
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    Answer: D. 16 to 20 weeks of gestation

    Most women first feel movement between 16 and 20 weeks, a little earlier in later pregnancies. At 6 to 8 weeks the embryo is far too small for the mother to feel it move.

11. A woman at 39 weeks whose membranes ruptured 30 hours ago has a temperature of 38.7 °C (101.7 °F), a tender uterus, a fast pulse, and foul-smelling fluid. You should suspect:

    1. A. Normal labor with a fever caused by dehydration
    2. B. Placenta previa with a secondary infection
    3. C. Infection of the amniotic fluid and membranes
    4. D. Pyelonephritis that has spread to the uterus
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    Answer: C. Infection of the amniotic fluid and membranes

    Prolonged rupture of membranes lets vaginal bacteria ascend and infect the fluid and membranes (chorioamnionitis). Fever, uterine tenderness, maternal and fetal tachycardia, and foul fluid are the classic signs. It threatens both mother and newborn, so expect neonatal sepsis risk. Dehydration does not cause a tender uterus or foul fluid.

12. The hormone detected by pregnancy tests, produced early by the developing placenta, is:

    1. A. Human chorionic gonadotropin
    2. B. Follicle-stimulating hormone
    3. C. Oxytocin
    4. D. Prolactin
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    Answer: A. Human chorionic gonadotropin

    Trophoblastic tissue makes hCG, which keeps the corpus luteum producing progesterone until the placenta takes over. Oxytocin acts at the end of pregnancy to drive contractions and milk letdown.

13. Normal pregnancy lasts about 40 weeks counted from the:

    1. A. Date of the first positive pregnancy test
    2. B. First day of the last menstrual period
    3. C. Day the patient first felt fetal movement
    4. D. Last day of the last menstrual period
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    Answer: B. First day of the last menstrual period

    Gestational age is counted from the first day of the last menstrual period, about 2 weeks before conception. Counting from the last day of the period is a common error that shortens the estimate.

14. A pregnancy is divided into trimesters. The second trimester spans about:

    1. A. Weeks 1 to 12
    2. B. Weeks 28 to 40
    3. C. Weeks 13 to 27
    4. D. Weeks 20 to 36
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    Answer: C. Weeks 13 to 27

    The first trimester covers weeks 1 to 12, the second weeks 13 to 27, and the third week 28 to delivery. Weeks 20 to 36 are the range where fundal height in centimeters tracks gestational age, not a trimester.

15. A healthy 30-year-old at 38 weeks loses about 800 mL of blood at delivery with little change in vital signs. This tolerance is explained by an increase in maternal blood volume during pregnancy of about:

    1. A. 30% to 50%
    2. B. 5% to 10%
    3. C. 75% to 100%
    4. D. 120% to 150%
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    Answer: A. 30% to 50%

    Plasma volume rises sharply, and red cell mass rises less, so total blood volume increases by roughly 30% to 50%. This reserve is why a pregnant woman can lose a large volume of blood before her vital signs change. An increase of 5% to 10% is far too small to explain that tolerance, while 75% to 100% or 120% to 150% greatly overstate it.

16. A woman at 30 weeks of gestation has a hemoglobin slightly below her prepregnancy value with no symptoms. This most likely reflects:

    1. A. Occult bleeding from a placental abruption
    2. B. Iron loss from the fetus taking her stores
    3. C. Hemolysis caused by fetal blood antigens
    4. D. Plasma volume rising more than red cell mass
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    Answer: D. Plasma volume rising more than red cell mass

    Physiologic, or dilutional, anemia of pregnancy occurs because plasma expands more than red cells. An asymptomatic mild drop is expected; abruption would cause pain, uterine tenderness, or bleeding.

17. A healthy 27-year-old at 34 weeks asks whether her faster pulse is normal. Compared with her prepregnancy baseline, a late-pregnancy resting heart rate is normally:

    1. A. 10 to 20 beats/min lower
    2. B. 10 to 20 beats/min higher
    3. C. Unchanged from baseline
    4. D. 40 to 50 beats/min higher
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    Answer: B. 10 to 20 beats/min higher

    Cardiac output rises 30% to 50%, partly through a higher heart rate. A rise of 40 to 50 beats/min is not normal and should prompt a search for blood loss, infection, or another cause.

18. During the second trimester, the blood pressure of a healthy pregnant woman typically:

    1. A. Rises steadily to 140/90 mmHg or higher
    2. B. Stays at the exact prepregnancy value
    3. C. Falls slightly, then returns to baseline
    4. D. Drops below 70 mmHg systolic at rest
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    Answer: C. Falls slightly, then returns to baseline

    Systolic and diastolic pressure dip by about 5 to 15 mmHg in the second trimester as vascular resistance falls. A pressure of 140/90 mmHg or more is never a normal change and suggests a hypertensive disorder.

19. Which respiratory change is normal late in pregnancy?

    1. A. Increased functional residual capacity at rest
    2. B. Decreased oxygen consumption by the tissues
    3. C. Higher resting PaCO2 than before pregnancy
    4. D. Increased tidal volume and minute ventilation
    Show answer

    Answer: D. Increased tidal volume and minute ventilation

    Progesterone drives deeper breathing, which raises minute ventilation and lowers PaCO2 to about 30 mmHg. Functional residual capacity actually falls as the uterus pushes up the diaphragm, which speeds desaturation during apnea.

20. A woman at 34 weeks with a severe asthma attack is working hard to breathe, and her ETCO2 is 42 mmHg. Given the normal respiratory changes of pregnancy, this value suggests that she:

    1. A. Is tiring and starting to retain CO2
    2. B. Has normal ventilation for late pregnancy
    3. C. Is blowing off CO2 because of anxiety
    4. D. Has progesterone slowing her breathing
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    Answer: A. Is tiring and starting to retain CO2

    Progesterone drives a higher minute ventilation in pregnancy, so the normal PaCO2 is about 28 to 32 mmHg. A value near 40 in a woman struggling to breathe means she can no longer keep up and is heading toward respiratory failure; treat aggressively and be ready to assist ventilation. A reading of 42 is therefore not normal for late pregnancy, even though it would be normal in a nonpregnant adult. Anxiety or hyperventilation would push CO2 below the pregnant baseline, not above it. Progesterone stimulates the respiratory drive; it does not slow breathing. (NAEPP asthma in pregnancy; Hegewald and Crapo.)

21. A 25-year-old at 36 weeks needs sedation for cardioversion. She ate 6 hours ago. You treat her as having a full stomach because in pregnancy:

    1. A. Gastric emptying speeds up and the sphincter tightens
    2. B. Gastric emptying slows and the sphincter relaxes
    3. C. Higher acid output fills the stomach faster
    4. D. The esophagus is compressed and blocked
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    Answer: B. Gastric emptying slows and the sphincter relaxes

    Progesterone relaxes smooth muscle, slowing gastric emptying and loosening the lower esophageal sphincter, while the uterus raises abdominal pressure. Emptying slows rather than speeds up, and the sphincter loosens rather than tightens. The risk does not come from extra acid output or a blocked esophagus but from stomach contents ready to reflux; the gag reflex remains intact.

22. A 31-year-old who delivered 10 days ago has a swollen, painful left calf. Which change of pregnancy, persisting after delivery, best explains her risk?

    1. A. Decreased clotting factor levels
    2. B. Lower platelet production
    3. C. A smaller plasma volume
    4. D. Increased clotting factor levels
    Show answer

    Answer: D. Increased clotting factor levels

    Clotting factors and fibrinogen rise in pregnancy to protect against hemorrhage at delivery, and this hypercoagulable state lasts for weeks after birth, raising the risk of deep vein thrombosis and pulmonary embolism. Plasma volume increases, not decreases, in pregnancy.

23. A 29-year-old at 35 weeks trips on a curb and says she has been unsteady on her feet for weeks. Pelvic ligament laxity from the hormone relaxin contributes to:

    1. A. A rigid pelvis that resists fracture
    2. B. Loss of sensation in the lower legs
    3. C. Altered gait and a higher risk of falls
    4. D. Decreased lumbar curvature of the spine
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    Answer: C. Altered gait and a higher risk of falls

    Loose joints and a forward-shifted center of gravity increase lumbar lordosis and make falls more likely. Lumbar curvature increases, not decreases, which is why back pain is common late in pregnancy.

24. The uterus grows from about 60 g before pregnancy to about what weight at term?

    1. A. About 1,000 g
    2. B. About 100 g
    3. C. About 250 g
    4. D. About 5,000 g
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    Answer: A. About 1,000 g

    The uterus enlarges roughly fifteenfold to about 1 kg, with a greatly increased blood supply. At term it receives a large share of cardiac output, so uterine injury can cause rapid, massive hemorrhage.

25. A 26-year-old at 30 weeks says she urinates far more often than before pregnancy, without pain or fever. Which normal change of pregnancy best explains this?

    1. A. Decreased renal blood flow and filtration
    2. B. Bladder shrinkage from low estrogen
    3. C. Higher GFR and pressure on the bladder
    4. D. Falling plasma volume late in pregnancy
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    Answer: C. Higher GFR and pressure on the bladder

    Renal blood flow and glomerular filtration rise by about half in pregnancy, producing more urine, and later the growing uterus and presenting part press on the bladder, so frequency without dysuria or fever is expected. Renal blood flow and filtration increase, not decrease. Estrogen levels are high, not low, in pregnancy, and the bladder does not shrink. Plasma volume rises by 40% to 50%; it does not fall late in pregnancy. Dysuria, fever, or flank pain would point instead to a urinary infection, which urinary stasis makes more common. (Williams Obstetrics, renal and urinary tract changes.)