Physiology of the First Stage 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 are some signs of labour?
Cervix dilating
Waters breaking
Mucus plug
What happens during 1st stage labour?
Can be difficult to identify
Irregular contractions
Effacement (thinning)
Dilation of the cervix
What are the stages of the first stage?
Latent phase
Active first stage
Transitional phase
Describe the latest phase
Irregular contraction
Dilation up 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 of contractions in 10 minutes
What are the mechanical factors that start labour?
Rupture of membranes
Fetal axis pressure
What role does oxytocin play?
Receptors in the uterus respond and the uterus contracts.
Pressure of the cervix = Activation of sensory nerves
What is cervical effacement?
The thinning of the cervix, this happens before dilation
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.
