Birth and first breath

Question 1

Why does progesterone prevent pre-term birth?

Answer 1

Inhibits uterine contractility and promotes cervical plug development

Question 2

How does oestrogen stimulate labour?

Answer 2

Softens cervix and stimulates uterus contraction - promotes connexion between myometrial cells and stimulates oxytocin receptor insertion into myometrium

Question 3

hCG in pregnancy

Answer 3

Produced by trophoblast

Supports CL

Question 4

Oestrogen in pregnancy

Answer 4

Declines sharply after birth

Question 5

When is progesterone produced from placenta?

Answer 5

After 12 weeks

Question 6

Where is relaxin produced?

Answer 6

Placenta and CL

Question 7

Function of relaxin

Answer 7

Softens cervix to prepare for labour, softens pelvic ligaments

Question 8

Which hormone changes start labour?

Answer 8

Decrease in progesterone, increase in CRH

Question 9

1st stage of labour

Answer 9

• Cervix at full dilation
• Painful contractions
• Arachidonic acid acted upon COX 1 and 2 to produce prostaglandin G and H
• Oxytocin stimulates contractions

Question 10

Where is oxytocin produced?

Answer 10

Posterior pituitary

Question 11

Which prostaglandin does oxytocin increase for labour?

Answer 11

PGF2-alpha

Question 12

what does PGDE2 do in pregnancy?

Answer 12

Relaxes cervix

Question 13

What does PGF2a do in pregnancy?

Answer 13

Contracts uterus

Question 14

2nd stage of labour

Answer 14

Delivery of foetus

Uterus contracts and mother pushes

Question 15

3rd stage of labour

Answer 15

Delivery of placenta
Haemostasis - oxytocin
PGF2a used to enhance contractions

Question 16

What is pneumothorax?

Answer 16

Burst alveoli - lung collapses and air gets Ito cavity

Question 17

How to help babies from inadequate surfactant

Answer 17

Administer surfactant/CPAP/increase oxygen

Question 18

Why is it important baby takes first breath quickly?

Answer 18

In utero, lungs full of amniotic fluid
After birth, breathing stimulates the removal of the fluid and replaces it with air
Stimulates surfactant secretion

Question 19

How is fluid removed from baby’s lungs?

Answer 19

Hormones stop foetal fluid production and initiate reabsorption
Some fluid forced out of trachea as baby passes along birth canal

Question 20

Surface tension

Answer 20

Tendency of liquid surfaces to pull together by molecular forces - creates meniscus

Question 21

Why is surface tension in alveoli bad?

Answer 21

Reduces lung compliance, makes collapse more likely

Question 22

How to calculate pressure in alveoli

Answer 22

Pressure = surface tension / radius

Question 23

Where is pulmonary surfactant secreted from?

Answer 23

Type ii alveolar cells

Question 24

What stimulates production of pulmonary surfactant?

Answer 24

Cortisol, thyroxine and prolactin

Question 25

Why is having surfactant good?

Answer 25

Pressure in small alveoli is higher than large ones = collapse at low lung volume
Smaller alveoli = increased surfactant concentration = lower surface tension in small alveoli more than large ones
Creates lung stability

Question 26

How are lungs stimulated to mature?

Answer 26

CRH from placenta stimulates anterior pituitary (mother) produces corticotropin - cortisol
CRH from placenta - baby - corticotropin - cortisol

Question 27

Which hormone stimulates lung maturation?

Answer 27

Cortisol

Question 28

What is produced from adrenal cortex in foetus?

Answer 28

DHEA and cortisol

Question 29

What does DHEA do when released from foetus?

Answer 29

Oestrogen production to support pregnancy