Physiology of first stage labour

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 is lightening?

Answer 8

At the end of pregnancy the baby will drop lower

Question 9

What are some signs of labour?

Answer 9

Cervix dilating
waters breaking
Mucus plug

Question 10

What happens during 1st stage labour?

Answer 10

Can be difficult to identify
Rhythmic and strong contractions
Effacement (thinning)
Dilation of the cervix

Question 11

What are the stages of the first stage?

Answer 11

Latent phase

Active first stage and transitional phase

Question 12

describe the latest phase

Answer 12

Irregular contraction
Dilation yp to 4 cm
Effacement

Question 13

Describe the active first stage

Answer 13

Regular contractions

dilation 4-10 cm

Question 14

Describe the transitional phase

Answer 14

cervix dilate 8-10cm

Question 15

How are contractions assessed?

Answer 15

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

Frequency is the number contractions in 10 minutes

Question 16

What are the mechanical factors that start labour?

Answer 16

Membranes- the formation of forewaters
Rupture of membranes

Fetal axis pressure

Question 17

What role does oxytocin play?

Answer 17

oxytocin is released in waves from the hypothalamus. Receptors in the uterus respond and the uterus contracts. pressure of the cervix = activation of sensory nerves

Question 18

Describe uterine action

Answer 18

contractions starts at the fungus and spreads across the downwards. It lasts longest in he fundus. Retraction is when the muscle fibres retrain some of the shortening of the contraction. Polarity- the upper pole of the uterus contracts and retracts, lower pole contracts slightly and dilates

Question 19

Describe engagement

Answer 19

Engagement had occurred when the widest presenting transverse diameter (biparietal) of the feat head has passed through the brim of the pelvis. In primigravida some head is normally engaged anytime from 36 weeks/ In multipara this may not occur until after the onset of labour. Engagement of the fetal head is usually measured in fifths palpable above the pelvic brim .

Question 20

What is cervical effacement?

Answer 20

The thinning of the cervix this happens before dilation.

Question 21

What can the colours of meconium mean?

Answer 21

Clear
Insignificant meconium
Significant meconium

Question 22

What are the mechanisms of birth?

Answer 22

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 23

What hormones are in the cocktail of hormones?

Answer 23

Oxytocin
Endorphins
adrenalin
prolactin
oestrogen
progesterone
relaxin

Question 24

What are the 4 major hormones active in labour?

Answer 24

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

Question 25

Describe oxytocin

Answer 25

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 26

Describe prolactin

Answer 26

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.

Question 27

Describe endorphins

Answer 27

Released from pituitary gland. Naturally occurring opiate. Feeling of pleasure, euphoria, and dependency. High levels during sex, pregnancy, labour and breastfeeding.

Stress hormone, is released during condition of pain and duress and acts as an analgesic. Like other stress hormones suppresses immune system helping the body not to reject the fetus. Facilitates release of prolactin during labour.

Question 28

Describe adrenaline/ Catecholamines (fight or flight)

Answer 28

Released from the adrenal gland. WAs in 1st stage labour inhibits oxytocin production. Reduces blood flow too the uterus, placenta and fetus. High levels of GAs during labour are associated with longer and adverse fetal heart patterns.

Question 29

What do CAs do when birth is imminent?

Answer 29

Sudden increases in CA levels at this stage activities fetal ejection reflex. Experiencing a sudden rush of energy. Upright and alert, dry mouth, shallow breathing. Urge to grab something. Expressing fear, anger and excitement. WAs will cause several very string contractions. After birth CA levels will drop steeply, mother will be feeling cool and shaky as a consequence. At this stage providing. warm atmosphere is important.

Question 30

Describe the hormonal systems in labour and birth

Answer 30

for birth to proceed optimally the limbic system must take precedence over the neocortex or rational brain. this shift can be helps by providing an atmosphere of quiet and privacy like low lighting. under such conditions a women intuitively will choose breathing sounds, movements and positions that are best for her, this is her genetic hormonal blue print.

Question 31

What are 2 factors that disturb birth?

Answer 31

Being in an unfamiliar environment

Being observed