Maternal changes in pregnancy

Question 1

Which hormones cause maternal changes in pregnancy?

Answer 1

Placental Peptides: hCG, hPL, GH

Maternal Steroids

Placenta & Foetal Steroids: progesterone, oestrodiol, oestriol

Maternal & Foetal Pituitary Hormones: GH, thyroid hormones, prolactin, CRF

Question 2

Describe the energy balance during pregnancy.

Answer 2

Increased energy output
-to cope with increased respiration and cardiac output

Increased energy storage
-for foetus, labour and puerperium (breast-feeding is calorific)

Question 3

Describe the Basal metabolic rate in pregnancy.

Answer 3

rises by 350 kcal/day mid-gestation
rises by 250 kcal/day late-gestation

75% of this increase is for foetus and uterus, 25% for respiration

Question 4

Describe the glucose changes during pregenancy.

Answer 4

1st trimester

• pancreatic β-cells increase producing more insulin
• plasma glucose decreases

2nd trimester
-hPL and oestrogen cause insulin resistance, increasing plasma glucose

Question 5

What is Gestational diabetes?

Answer 5

diabetes during pregnancy

-common in 2nd trimester due to insulin resistance from hPL and oestrogen

Question 6

What is the Effect of pregnancy on total water gain?

Answer 6

oestrogen and progesterone affect the renin/angiotensin axis by causing:

• thirst
• fluid retention
• sodium retention
• decrease in plasma oncotic pressure (albumin levels drop)
• resetting of osmostat
• total increase in plasma volume and this will be distributed to different areas
• very common for some of it to end up in oedema

Question 7

How is Respiration affected during pregnancy?

Answer 7

oestrogen & progesterone affect repiratory centre in the brain:

• increased sensitivity to CO2
• women breathe more deeply
• increase in minute volume by 40%
• therefore increase in arteriole PO2 (10%) and decrease in PCO2 (15-20%)

Question 8

Describe the Gas transfer between mother and foetus.

Answer 8

high maternal PO2 and low maternal PCO2 facilitates gas transfer:

• high O2 causes O2 transfer to foetus
• low CO2 causes foetal CO2 (waste) to be transferred back into mum, providing foetal protection

Question 9

What is the Effect of pregnancy on maternal blood?

Answer 9

40-50% increase in plasma volume
20% increase in red blood cells

HAEMODILUTION
-more plasma serum and less red blood cells (apparent anaemia)

• increase in white blood cells and clotting factors; blood becomes hypercoagulable, increasing risk of thrombosis
• increased efficiency of iron absorption from gut

Question 10

Describe the foetal blood during pregnancy.

Answer 10

increased Hb with altered type (HbF)

• increased O2 affinity than maternal Hb (HbA)
• therefore oxygen given up by HbA to HbF

foetus has higher Hb concentration than mother

Question 11

What is the effect of smoking on the foetus?

Answer 11

causes foetal hypoxia because more maternal carboxy-Hb, stopping transfer of oxygen to foetus because carboxy-Hb is more permanent

Question 12

Descibe the Cardiovascular changes in pregnancy.

Answer 12

Changes in ECG and heart sounds

• expanding uterus pushes heart around
• murmurs develop due to high blood flow

Increased Cardiac Output

• increased heart rate and stroke volume
• for maternal muscle (uterus), skin, kidneys and foetal supply across placenta

Blood Vessels
-lower blood pressure despite greater CO due to a greater reduction in TPR by vasodilation

Question 13

Describe the Effect of steroids during pregnancy on GI Tract.

Answer 13

• increased appetite and thirst
• reduced GIT motility (causes constipation)
• relaxes Lower Oesophageal Sphincter (causes acid reflux)

Question 14

What is folic acid used as a supplement for?

Answer 14

DNA production

growth

blood cells

Question 15

Which neural defect is folic acid deficiency linked to?

Answer 15

neural tube defect called spina bifida

Question 16

Describe the Urinary system changes in pregnancy.

Answer 16

smooth muscle relaxation in urinary tract:

• bladder
• ureters
• collecting systems in kidney

increased diuresis due to increased CO
increased clearance of creanine, urea, uric acid

Question 17

Why are pregnant women more prone to UTIs?

Answer 17

due to urinary stasis from smooth muscle relaxation

Question 18

Describe the Micturition in pregnancy.

Answer 18

in 1st trimester, uterus enlarges compressing the bladder and increasing urinary frequency

in 2nd trimester, uterus is lifted out of the pelvis and there is less pressure on bladder, normal micturition

in 3rd trimester foetus head compresses bladder and increases urinary frequency

Question 19

Explain the Changes in uterine size during pregnancy.

Answer 19

hypertrophy: huge increase in muscle mass
huge increase in blood flow

*placenta+uterus receive 1/6 of total blood supply (hence a lot of bleeding during C-section)

Question 20

Describe the Changes in uterus during pregnancy.

Answer 20

isthmus (lower part of the uterus) expands and is less muscular and more fibrous, forming the lower uterine segment, which acts as a funnel to allow baby to come down

top of the uterus still muscular to push baby down

Question 21

Where is the incision made during a C-section?

Answer 21

lower segment C-section because there is less bleeding when there is less muscle and more fibrous structures

Question 22

Describe the Changes in the cervix during pregnancy.

Answer 22

• increase in vascularity
• connective tissue softens from 8 weeks to begin gradual preparation of expansion
• proliferation of mucosal glands, greatly increasing mucosal production (protective, anti-infective)

Question 23

Cervix during labour is softened by…

Answer 23

inflammatory mediators and prostaglandins

Question 24

Describe the Maternal changes after pregnancy.

Answer 24

Returns to normal:

• dramatic & rapid fall in steroids on delivery of placenta
• most endocrine driven changes return to normal rapidly
• uterine muscle rapidly loses oedema but contracts slowly and never returns to pre-pregnancy size
• removal of steroids (oestrogen and progesterone) permits action of raised prolactin on breast for breastfeeding