Physiology of the First Stage

Question 1

What is the description of physical labour?

Answer 1

The process by which the fetus, placenta and membranes are expelled through the birth canal

Question 2

What is 1st stage of labour?

Answer 2

Cervix is 0-10 cm dilated

Question 3

What happens in 2nd stage labour?

Answer 3

Cervix fully dilated to birth of baby

Question 4

What happens in 3rd stage labour?

Answer 4

Birth of baby to delivery of placenta

Question 5

What happens during the last weeks of preganacy?

Answer 5

• Mood swings
• Lightening
  (pelvic floor relaxed and softened)
• Difficulty walking
• Backache
• Venous congestion of pelvis
• Increased vaginal secretion
• Increased frequency of micturition, urgency and stress incontinence
• Non progressive Braxton Hicks
• Changes in hormones
• Oxytocin receptors are developed

Question 6

How does labour start?

Answer 6

It is not fully understood. Hormonal factors, interaction of maternal and fetal hormones.

Question 7

Describe the hormonal factors that help to start labour?

Answer 7

Sharp increases in oestrogen levels overcome the inhibiting effects of progesterone. This displays the oxytocin receptors. Placenta releases PGs. this produces an enzyme that digests collagen un cervix.

Question 8

What are some signs of labour?

Answer 8

Cervix dilating
Waters breaking
Mucus plug

Question 9

What happens during 1st stage labour?

Answer 9

Can be difficult to identify
Irregular contractions
Effacement (thinning)
Dilation of the cervix

Question 10

What are the stages of the first stage?

Answer 10

Latent phase
Active first stage
Transitional phase

Question 11

Describe the latest phase

Answer 11

Irregular contraction
Dilation up to 4 cm
Effacement

Question 12

Describe the active first stage

Answer 12

Regular contractions

Dilation 4-10 cm

Question 13

Describe the transitional phase

Answer 13

Cervix dilate 8-10cm

Question 14

How are contractions assessed?

Answer 14

Strength - mild is less than 30 secs
Moderate between 30-50 secs
strong more than 50 secs

Frequency - is the number of contractions in 10 minutes

Question 15

What are the mechanical factors that start labour?

Answer 15

Rupture of membranes
Fetal axis pressure

Question 16

What role does oxytocin play?

Answer 16

Receptors in the uterus respond and the uterus contracts.

Pressure of the cervix = Activation of sensory nerves

Question 17

What is cervical effacement?

Answer 17

The thinning of the cervix, this happens before dilation

Question 18

What are the mechanisms of birth?

Answer 18

Engagement
Descent
Flexion
Internal Rotation
Crowning
Extension
Restitution
External Rotation of the head and internal rotation of the shoulders
Lateral flexion, followed by the birth of the shoulders and trunk

Question 19

What hormones are in the cocktail of hormones?

Answer 19

Oxytocin
Endorphins
adrenalin
prolactin
oestrogen
progesterone
relaxin

Question 20

What are the 4 major hormones active in labour?

Answer 20

Oxytocin is the hormones of love
Endorphines are hormones of pleasure
Adrenalin is the hormone of excitement
Prolactin is the mothering hormone

Question 21

Describe oxytocin

Answer 21

Hormone of love. Active in sex activities, birth and breastfeeding. Released from the pituitary gland in pulses. Responsible for ejection relaxes, sperm ejection, fetus injection, placenta ejection and milk ejection reflex.

Question 22

Describe prolactin

Answer 22

Mothering hormone, produces aggressively protective behaviour. Also produces some level of anxiety that helps in breastfeeding relationship, mother needs to be vigilant and out her baby’s needs first. Milk production hormone.