PMC Prenatal Anatomy & Physiology 3 — Questions and Answers
Question 1: Which nerve is most commonly compressed in carpal tunnel syndrome during pregnancy, and why?
- Ulnar nerve due to elbow flexion
- Median nerve due to fluid retention and edema (Correct answer)
- Radial nerve due to wrist extension
- Axillary nerve due to shoulder girdle shift
Correct answer: Median nerve due to fluid retention and edema
The median nerve is compressed within the carpal tunnel by pregnancy-related fluid retention that increases compartment pressure.
Question 2: The hormone responsible for stimulating breast tissue growth (mammogenesis) and suppressing lactation during pregnancy is primarily:
- Prolactin
- Progesterone (Correct answer)
- Human placental lactogen
- Oxytocin
Correct answer: Progesterone
High progesterone levels during pregnancy inhibit milk secretion despite rising prolactin, allowing mammary gland development without lactation.
Question 3: Physiologic lordosis increases during pregnancy primarily because of:
- Relaxin softening the intervertebral discs
- Anterior shift of the center of gravity from uterine weight (Correct answer)
- Decreased activity of the erector spinae muscles
- Progesterone-induced disc swelling
Correct answer: Anterior shift of the center of gravity from uterine weight
The anterior displacement of the center of gravity by the gravid uterus causes compensatory lumbar hyperlordosis.
Question 4: Which fetal structure allows blood to bypass the lungs by connecting the pulmonary artery to the aorta?
- Foramen ovale
- Ductus venosus
- Ductus arteriosus (Correct answer)
- Umbilical vein
Correct answer: Ductus arteriosus
The ductus arteriosus shunts blood from the pulmonary artery to the descending aorta, bypassing the fluid-filled fetal lungs.
Question 5: Which maternal anatomical structure is most directly responsible for round ligament pain experienced in the second trimester?
- Ovarian ligament stretching over the iliac crest
- Round ligament being stretched as the uterus rises and rotates (Correct answer)
- Piriformis compression of the sciatic nerve
- Pubic symphysis widening from relaxin
Correct answer: Round ligament being stretched as the uterus rises and rotates
As the uterus rapidly grows and slightly rotates, the round ligaments are stretched, causing sharp inguinal or lower abdominal pain.
Question 6: Human chorionic gonadotropin (hCG) is produced by which structure and serves what primary function in early pregnancy?
- Anterior pituitary; stimulates ovarian follicle growth
- Syncytiotrophoblast; maintains the corpus luteum to sustain progesterone (Correct answer)
- Corpus luteum; triggers uterine implantation
- Decidua; prevents premature uterine contractions
Correct answer: Syncytiotrophoblast; maintains the corpus luteum to sustain progesterone
hCG is produced by the syncytiotrophoblast of the developing placenta and signals the corpus luteum to keep producing progesterone.
Question 7: During pregnancy, the glomerular filtration rate (GFR) increases by approximately:
- 10–15%
- 25–30%
- 50% (Correct answer)
- 70–80%
Correct answer: 50%
GFR increases by about 50% during pregnancy, reflecting increased renal plasma flow to handle the elevated metabolic demands.
PMC Prenatal Anatomy & Physiology 3
Which nerve is most commonly compressed in carpal tunnel syndrome during pregnancy, and why?