Hormones, perineum, fetal circulation

Oxytocin

Beta-endorphin

• Suckling
• Nipple/clitoral stimulation
• Pressure on cervix
• Perineal stretching

• Increased stress, fear or anxiety
• Episiotomy (reduces stretching)
• Induction/augmentation of labour, flooding oxytocin receptor sites, having opposite effect
• This can cause prolonged labour, increased likelihood of post-partum haemorrhage and a reduction in nurturing behaviour between mother and baby

Called the 'coping hormone' - natures pain reliever. Can modify perceptions of pain

Catecholamines

Initiate 'fight or flight' response, causes shunt of blood from non-vital organs such as uterus. Causes lack of blood flow and oxygen to uterus which in turn causes more painful contractions and reduces oxygen available to fetus which can cause hypoxia

• First degree - perineal skin only
• Second degree - perineal muscle and skin
• Third degree - skin, muscle and partial or complete disruption of anal sphincter
• Fourth degree - skin, muscle and complete disruption of external and internal anal sphinter

• Levator ani muscles thin out and are displaced laterally
• Superficial layer of pelvic floor stretch & transverse perineal muscles separate
• Rectum compressed
• Perineal body flattened

• Maternal request
• Pre-term labour (before 37 weeks)
• Post-term labour (after 42 weeks)
• Induction/augmentation of labour
• Diabetes
• Ante-partum haemorrhage
• Maternal diabetes
• Renal failure
• Cardiac disease
• PROM (over 24 hours ago)
• Breech presentation
• Previous section

• Intra-uterine growth restriction (IUGR)
• Oligohydramnios
• Prematurity
• Meconium stained liquor
• Multiple pregnancy
• Uterine infection

• Epidural
• Fresh meconium stained liquor
• Vaginal bleeding in labour
• Oxytocic augmentation of labour
• Pyrexia - 38 degrees once or 37.5 degrees twice two hours apart
• Abnormal fetal heart heard during labour or abnormal uterine activity

• Mother can hear
• Does not limit mobility
• Limited intervention

Unable to detect variability in fetal heart rate

Change in heart rate - normal is around 5-25 bpm from baseline rate

• Alternating of the fetus from sleep to activity stages.
• 20-40 mins of reduced variability (<5 bpm) - 'rest phase'
• 40-90 mins is non-reassuring
• Over 90 mins is abnormal

An increase of 15 or more bpm from baseline rate lasting for 15 seconds or longer

• A reduction of 40 or more bpm for up to 60 secs. This usually occurs during a contraction and caused by cord compression and lack of oxygen. A healthy baby will return to baseline fairly quickly.
• Atypical deceleration - lasting longer than 60 secs and slow return to baseline. Indicates fetal hypoxia.

• DR - Define Risk
• C - Contractions
• BRA - Baseline RAte
• V - Variability
• A - Accelerations
• D - Decelerations
• O - Overall

• Ductus venosus - shunts blood past liver
• Foramen ovale - allows blood to shunt from right atrium to left atrium
• Ductus arteriosus - shunts blood past pulmonary artery
• Hypogastric arteries - take blood back to placenta via umbilical arteries

• Ductus venosus becomes ligamentum venosum
• Foramen ovale becomes fossa ovalis
• Ductus arteriosus becomes ligamentum arteriosum
• Hypogastric arteries become lateral umbilical ligaments