Normal delivery Flashcards
What is the birthplace in England cohort study?
Study that collected data on labour, delivery and birth outcomes
Compared 4 settings
- Home
- Free-standing midwifery unit
- Alongside midwifery unit
- Obstetric unit
Findings:
- Giving birth is safe, no difference in adverse outcomes when midwife led/ alongside midwifery unit compared, first baby at home is more risky - no difference if 2nd or 3rd baby
Define labour
Period between onset of contractions until placenta delivered
Which hormone inhibits uterine contractility?
Progesterone
Pro gestation
Which hormones stimulate uterine contractility?
Prostaglandins and oxytocin
What is necessary for delivery to occur?
1) Uterus must be capable of regular, synchronised contractions
2) Structure of the cervix must change
What is the peurperium?
Period in which the body returns to its non pregnant state
What is the onset of labour?
Point when uterine contractions become regular and cervical effacement and dilatation becomes progressive
Characteristics of labour
- Onset of contractions
- Cervical effacement
- Rupture of membranes
- Birth of baby
- Delivery of placenta and membranes
Discuss the first stage of labour
2 phases: latent and established stages
Latent stage: onset of contractions > 4cm dilation
Cervix thins and begins to dilate mediated by prostaglandins and relaxin which causes elastic fibres in the cervix to be enzymatically degraded allowing for softening
Established stage: 4cm > full dilatation
Contractions are regular and women need one-one from a midwife
What is the latent stage of labour?
First part of the first stage of labour
Onset of contractions > 4cm dilation
Cervix thins due to prostaglandin release which causes elastic fibres in the cervix to be degraded
Foetal fibronectin is released
What is foetal fibronectin?
Fetal fibronectin (fFN) is a protein produced at the boundary between the amniotic sac and the lining of the uterus (the decidua)
Fetal fibronectin is a protein that’s believed to help keep the amniotic sac “glued” to the lining of the uterus
What is mifepristone?
Progesterone antagonist
Used to prime the uterus for contractions
Used with misoprostol to induce delivery following the death of a foetus
Are misoprostol + mifespristone used to induce contractions in live pregnancies?
No - they are not generally used to induce contractions in live pregnancies because the contractions they cause can’t be controlled and can be too frequent which would cause foetal hypoxia
What is used to artificially induce labour?
Intravaginal prostaglandins - soften cervix and causes mild uterine contractions
How long does the first stage of labour last?
12-14hrs nulliparous
6-8hrs parous
What is used to control the frequency and force of contractions in women who have been induced?
Oxytocin - has a short half life so can be controlled
Oxytocin stimulates the uterine muscles to contract, so labor begins. It also increases the production of prostaglandins, which move labor along and increases the contractions even more
What happens to the placenta during the first stage of labour?
Placental blood flow decreases as a result of occlusion of the spiral arteries during uterine contractions. When the contractions end, legs volumes of maternal blood enter the intervillous spaces allowing for gas transfer. If the contractions become too frequent less gas exchange occurs which could lead to foetal hypoxia
Stages of cervix dilation
What is the established stage of labour?
Second part of the first stage
Starts when cervix is 4cm dilated and ends when it is 10cm dilated
Contractions are regular and women need one-to-one care from a midwife and is not left alone. Women should eat snacks or a light meal, unless on opioids because they cause sickness and possible vomit aspiration
What is a partogram?
Graphical representation of labour
- Maternal obs
- Cervical dilation
- Foetal well-being
- The frequency of contractions is documented every 30mins (describes as the number of contractions every 10mins
- Maternal pulse rate measured hourly
- Maternal blood pressure and temp measured every 4hr
- Volume of urine passed also documented to ensure the woman is hydrated by avoiding a full bladder as this can slow labour
When are women offered a vaginal examination during labour?
Every 4h to establish progress, the cervix should dilate at a rate of 2cm every 4h
What are the phases of the second stage of labour?
Passive phase: foetal head is pushed only by uterine contractions down through the pelvis
Active phase: passage of foetal head is assisted by uterine contractions and voluntary pushing
What would a long passive phase suggest?
Passive stage = first phase of second stage of labour
Foetal head is pushed by uterine contractions
Prolongation suggests malposition of the foetus or ineffective contractions - a long passive phase increases the risk of postpartum haemorrhage and maternal infection
How is a long passive phase managed?
Women are encouraged to push and oxytocin can be used
How frequently are women examined during the second stage of labour?
Every hr
What is meant by ‘cardinal movements of labour?’
As the foetus passes through the birth canal the direction of the head changes to accommodate the bends imposed by the bony pelvis.
Cardinal movements of labour in order
- Engagement: the foetus is engaged when the widest parts of its head have passed the pelvic inlet. The lowest part of the head (known as the vertex) can be felt 1cm above the ischial spines
- Descent: downward movement of the foetal head occurs with uterine contractions
- Flexion: descent is most efficient when the foetal head is flexed. Uterine contractions force the foetal head forwards as it presses against the lower segment of the uterus. This ensures that the smallest diameter of the head passes through the birth canal
- Internal rotation: the foetal head gradually rotates so that the occipital can’t pass below the symphysis pubis. By rotating the foetal head maintains the smallest presenting diameter
- Extension: further contractions aided by voluntary pushing from the mother force the occiput under the symphysis pubis. This causes extension of the foetal head as the birth canal curves upwards. The head delivers through the vaginal introitus by extension. The occiput delivers first followed by the bregma, forehead, nose then chin
- Restitution and external rotation: as the head delivers it rotates back to the position in which it entered the birth canal so that the anterior shoulder lies under the symphysis pubis and the posterior shoulder lies in front of the sacral promontory
- Expulsion: birth is completed with delivery of the anterior shoulder and lateral flexion of the head to facilitate delivery of the posterior shoulder
What 3 factors does the passage of the head depend on?
- Power: the expulsive force supplied by uterine contractions and in the second stage by voluntary pushing by the mother
- Passage: the diameter of the birth canal
- Passenger: position, flexion and size of the foetal head affected by the rate of descent
What are the maternal adaptations that facilitate the passage of the foetus down the birth canal?
Shape of the female pelvis, wider and shallower than the male pelvis
What is an episiotomy?
- Surgical incision in the perineum to increase the size of the vagina opening. Restricted for cases of foetal compromise or instrumental delivery. Performed when the head has crowned and the perineum is maximally stretched
- A posterior episiotomy is usually done, scissors are used to make a mediolateral cut from the fourchette usually towards the right
- An anterior cut may be needed for women who have had suffered FGM
- Suturing is needed immediately after immediately after delivery of placenta
Discuss perineal trauma
1st degree: perineal skin alone
2nd degree: perineal muscle
3rd: involves anal sphincter
4th: involves external anal sphincter, internal anal sphincter and anal epithelium
Discuss variability in HR measurement as part of the CTG
Healthy foetus will constantly adapt their HR
Variability indicates an intact nervous system
If there is no variation, the foetus is not responding appropriately
Most common cause is that the baby is asleep (should occur for no more than 40 mins)
Change of >5bpm = reassuring
<5bpm change for 40-90 mins = not reassuring but baby may be asleep
<5bpm change for >90 mins = abnormal
Discuss decelerations relating to CTG monitoring
Decelerations means baby’s HR is decreasing by >15bpm for >15s
Absence of this is reassuring
Early decelerations start when the uterine contraction begins and recover when uterine contraction stops - this is normal amd occurs because contractions compress baby’s head is compressed which raised ICP and reduced vagal tone
Late decelerations occur after the start of the contraction and do not return to normal until 30 seconds after contraction ends - this is a sign of foetal distress
Variable decelerations are associated with cord compression
What is a sinusoidal pattern on CTG?
Rare but worrying sign, undulating pattern with no variability
Can indicate foetal anaemia
If occuring in short spells can be associated with foetal behaviour e.g. thumb sucking
Should always be taken seriously - scan MCA for blood velocity to look for anaemia
Pros and cons of spinal and epidural
Spinal: majority of cases in UK, bupivacaine used, LA injection into CSF in subarachnoid space
Easier than epidural, most reliable way to produce dense bilateral block, patients have absolutely no sensation with this block
Two ‘pops’ one>ligamentum flavum, two>arachnoid mater >> you see CSF
Disadvantages: may cause severe hypoTN and can wear off
Epidural: good anaesthesia but not profound so patients still feel pressure, surgeons hand etc, good because catheter stays in place so top up can be given
Disadvantages: patchy block, tricky, takes longer to insert
