T2 L18: Physiology of pregnancy

Question 1

How are the 3 pregnancy semesters split?

Answer 1

First - <12 weeks
Second - <26 weeks
Third - >27 weeks

Question 2

What are the 3 main hormones involved in pregnancy?

Answer 2

BHCG- there is a dramatic raise in the first days-week. It’s released from the corpus luteum initially and then by the placenta

Progesterone- Pro-gestation. It keeps the state of quiescence

Oestrogen- for breast growth and areolar enlargement

Other hormones are inhibin, relaxin, and TSH

Question 3

What is quiescence?

Answer 3

Inactivity or dormancy

Question 4

What is the function of human chorionic gonadotrophin (hCG)?

Answer 4

It maintains corpus luteum secretion of oestrogen and progesterone. It decreases as the levels of placental progesterone increase

Beta- pregnancy testing
Alpha- mimics LH, FSH, and TSH

Question 5

Which cells produce hCG?

Answer 5

Trophoblasts

Question 6

What is the function of human placental lactogen (hPL)?

Answer 6

It works by altering maternal carbohydrate and lipid metabolism to provide a steady state of glucose for foetal requirements

It has a similar structure to prolactin and growth hormone. Larger placentas produce more hPL

Question 7

What is the function of human placental gonadotrophin (hPG)?

Answer 7

It induces maternal insulin resistance to regulate foetal growth

Question 8

High levels of which hormone cause vomiting in pregnancy (hyperemesis)?

Answer 8

hCG

Question 9

What is the function of progesterone during pregnancy?

Answer 9

• It relaxes smooth muscle everywhere causing constipation, gastric reflux, and supra-pubic dysfucntion
• Maintains uterine quiescence by decreasing uterine electrical activity
• Lobulo-alveolar development in breasts
• Substrate for foetal adrenal corticoid synthesis

Question 10

What is the function of oestrogen in pregnancy?

Answer 10

• Causes growth of the uterus and cervical changes
• development of the breast ductal system
• Stimulates prolactin synthesis

Question 11

What are some haematological changes during pregnancy?

Answer 11

• 40% increase in plasma volume
• 25% increase in RBC’s
• Plasma colloid osmotic pressure falls causing a shift of fluid into the extracellular spaces
• Increase in clotting factors causing a hypercoagulable state

Question 12

What are some respiratory system changes during pregnancy?

Answer 12

increased oxygen demands so there is an increase in maternal pO2 and increased availability of O2 into tissues

Question 13

What respiratory symptoms may a pregnant woman experience?

Answer 13

• Splinting of diaphragm
• Raised HR leads to palpitations
• Oedema due to increase in plasma volume
• Low BP causing fainting/ dizziness
• Decreased exercise tolerance

Question 14

What is diaphragm splinting?

Answer 14

Sharp pains during inspiration because of changes to the angles of the diaphragm

Question 15

What are some musculoskeletal/dermatological symptoms of pregnancy?

Answer 15

• Increased lumbar lordosis
• Hypermobile joints
• Stretch marks
• Changes in skin pigmentation Eg. linear nigra, melasma, darkened nipple
• Carpel tunnel because of the increased pressure around the wrists
• Sciatica
• Cramps

Question 16

What is melasma?

Answer 16

Darkened pigmentation on the face

Question 17

What is sciatica?

Answer 17

Pain caused by an irritated nerve and can be treated with exercises and stretches

Question 18

What are some urological changes during pregnancy?

Answer 18

• Kidneys increase 1cm in size and increase their flow by 50% so there is increase GFR
• Plasma levels of creatine and urea decrease
• Dilated ureters due to the progesterone
• Increased pressure causing increased urinary frequency

Question 19

What are some thyroid changes during pregnancy?

Answer 19

• Increased serum T3 and T4 levels

- Increase in thyroid binding globulin