Physiology in Pregnancy

Question 1

Give 3 ways to estimate the date of delivery.

Answer 1

Use Naegele’s rule: add 7 days to 1st day of LMP, subtract 3 months, add 7 days, add 1 year. Ultrasonic examination - measurement of crown-to-rump length in first trimester. Measure of fundal height - from the pubic symphysis to highest part of the uterus (reaches umbilicus at 20 weeks).

Question 2

What is Naegele’s rule?

Answer 2

Add 7 days to 1st day of LMP, subtract 3 months, add 7 days, add 1 year.

Question 3

How is the fundal height measured?

Answer 3

From the pubic symphysis to highest part of the uterus .

Question 4

What happens to blood volume during pregnancy?

Answer 4

Increases up to 40 weeks. Once placenta out, it drops.

Question 5

What happens to stroke volume, heart rate and cardiac output during pregnancy?

Answer 5

All increase.

Question 6

Why does blood pressure decrease during pregnancy?

Answer 6

Due to progesterone-induced vasodilation; BP = CO × systemic vascular resistance (SVR).

Question 7

What happens tidal volume, oxygen consumption and basal metabolic rate during pregnancy?

Answer 7

All increase.

Question 8

Mild respiratory alkalosis is as a result of what during pregnancy?

Answer 8

Hyperventilation.

Question 9

Why do pregnancy patients become anaemic during pregnancy?

Answer 9

Plasma > RBC volume → hemodilution. ↓ hematocrit (ratio of the volume of red blood cells to the volume of blood - physiologic anemia.

Question 10

Why do bicarbonate ions fall during pregnancy?

Answer 10

They are excreted from the kidneys as renal compensation for respiratory alkalosis.

Question 11

Give 2 gastrointestinal symptoms of pregnancy.

Answer 11

Nausea. Vomiting (AKA “morning sickness” ). Constipation. Heartburn (pyrosis). Oesophageal reflux. Intrahepatic cholestasis of pregnancy due to ↓ gallbladder emptying time → ↑ risk of cholelithia (impair release of bile from liver cells).

Question 12

Why is there nausea in pregnancy?

Answer 12

Reduced peristalsis.

Question 13

What happens to progesterone levels, kidney size and kidney volume during pregnancy?

Answer 13

All increase.

Question 14

Why does urinary frequency increase during the first trimester of pregnancy?

Answer 14

Gravid uterus presses on bladder → urinary frequency, nocturia, stress incontinence.

Question 15

Why does urinary frequency decrease during the second trimester of pregnancy?

Answer 15

Second trimester: uterus occupies abdominal space → ↓ urinary frequency

Question 16

Why does parathyroid hormones increase during pregnancy?

Answer 16

Increase in parathyroid hormone (PTH) ensures regulation of serum calcium (meets calcium need of developing fetal skeleton).

Question 17

Why are FSH and LH levels almost undetectable during pregnancy?

Answer 17

High levels of oestrogen and progesterone.

Question 18

What happens to aldosterone and renin levels during pregnancy?

Answer 18

Both increase to increase blood volume.

Question 19

What stimulates prolactin to rise during pregnancy?

Answer 19

Oestrogen stimulates pituitary prolactin release.

Question 20

Why do cortisol levels rise during pregnancy?

Answer 20

Physiologic hypercortisolism ▫↑ need for estrogen, cortisol → ↑ glucocorticoids from adrenal glands →supports fetal somatic, reproductive growth.

Question 21

What happens to the pancreas during pregnancy?

Answer 21

Hypertrophy. Diabetogenic state” of pregnancy ▫↑ need for glucose, insulin production →hypertrophy, hyperplasia of pancreatic beta cells.