Physiology of first stage labour Flashcards
What is the description of physical labour?
The process by which the fetus, placenta and membranes are expelled through the birth canal
What is 1st stage of labour?
cervix is 0-10 cm dilated
What happens in 2nd stage labour?
Cervix fully dilated to birth of baby
What happens in 3rd stage labour?
Birth of baby to delivery of placenta
What happens during the last weeks of preganacy?
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
How does labour start?
It is not fully understood. Hormonal factors, interaction of maternal and fetal hormones.
Describe the hormonal factors that help to start labour?
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.
What is lightening?
At the end of pregnancy the baby will drop lower
What are some signs of labour?
Cervix dilating
waters breaking
Mucus plug
What happens during 1st stage labour?
Can be difficult to identify
Rhythmic and strong contractions
Effacement (thinning)
Dilation of the cervix
What are the stages of the first stage?
Latent phase
Active first stage and transitional phase
describe the latest phase
Irregular contraction
Dilation yp to 4 cm
Effacement
Describe the active first stage
Regular contractions
dilation 4-10 cm
Describe the transitional phase
cervix dilate 8-10cm
How are contractions assessed?
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
What are the mechanical factors that start labour?
Membranes- the formation of forewaters
Rupture of membranes
Fetal axis pressure
What role does oxytocin play?
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
Describe uterine action
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
Describe engagement
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 .
What is cervical effacement?
The thinning of the cervix this happens before dilation.
What can the colours of meconium mean?
Clear
Insignificant meconium
Significant meconium
What are the mechanisms of birth?
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
What hormones are in the cocktail of hormones?
Oxytocin Endorphins adrenalin prolactin oestrogen progesterone relaxin
What are the 4 major hormones active in labour?
Oxytocin is the hormones of love
Endorphines are hormones of pleasure
Adrenalin is the hormone of excitement
Prolactin is the mothering hormone
Describe oxytocin
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.
Describe prolactin
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.
Describe endorphins
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.
Describe adrenaline/ Catecholamines (fight or flight)
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.
What do CAs do when birth is imminent?
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.
Describe the hormonal systems in labour and birth
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.
What are 2 factors that disturb birth?
Being in an unfamiliar environment
Being observed
