Childbirth & Mechanisms of Labour Flashcards
What causes the onset of labour (basic)?
-Likely multi factorial
-Foetal factors
-Progesterone withdrawal theory
-Corticotrophin releasing hormone
What is labour?
Regular uterine (smooth muscle) contractions
What are the 2 phases of labour?
-Latent = cervix begins to soften & have irregular uterine contractions
-Active = cervix dilates from 4cm to fully dilated (10cm) & are experiencing regular uterine contractions
When is the 1st, 2nd & 3rd stage of labour?
1st stage:
-0-4cm coincides with latent phase
-4-10cm coincides with active phase - onset of regular, rhythmic contractions until full dilatation (10cm)
2nd stage:
From full dilatation of cervix to delivery of baby
3rd stage:
-From delivery of baby to delivery of placenta & membranes
-May involve active Mx (~30min) - or physiological Mx (~60min)
What is within the 1st stage of labour?
Contractions cause dilation of cervix
Cervix begins to soften = latent phase – irregular contractions
Wait for latent phase to become established labour
Established/active labour = 4cm dilated & regular contractions
Established labour lasts until..
Fully dilated = 10cm dilated
End of 1st stage – urge to push may start
May speed up labour by artificially breaking waters (ARM – artificial rupture of the membranes) or oxytocin drip (drug aka syntocinon) = both increase strength of contractions
What is within the 2nd stage of labour?
Begins when cervix = fully dilated (10cm)
Ends = birth of baby
Mother finds position to give birth in
Urges to push – can do so during contractions (if have epidural may have no urges to push)
This stage lasts 2-3 hours
As baby’s head almost out –s top pushing & take short breaths – slow – to give perineum time to stretch
May involve episiotomy – cut perineum (prevents tears & speeds up)
After birth of head – rest of body born in following 1-2 contractions
Skin-to-skin with baby
What is within the 3rd stage of labour?
Starts once baby is born
Involves womb contraction & placenta delivery
X2 ways to manage:
Active -> treatments speed up process
-Inject oxytocin into thigh during birth or after = causes womb contraction
-Midwife waits 1-5 mins & then cuts umbilical cord (immediately if around baby’s neck)
-So placenta comes away from womb – midwife will pull on umbilical cord so placenta pulled out vagina = within 30 mins after deliver baby
Physiological -> no treatments – allow to happen naturally
-Umbilical cord only cut once pulsing stops – so blood passes to baby until this (2-4 mins)
-Urge to push returns – to push out placenta -> can last up to 1hr for placenta to come away from womb (few mins for actual placenta to come out once comes off womb)
Duration of labour - normally?
1st pregnancy = 12-14 hours (shorter duration for subsequent pregnancies)
Name the 4Ps of labour/birth say what they mean - & explain what the 4 are used for in general.
(1.) Power = uterine contractility & maternal effort
(2.) Passage = maternal bony pelvis or soft tissue of birth canal
(3.) Passenger = presentation or position of foetus
(4.) Psyche = confidence, encouragement & +ve affirmation
–> cervical effacement, dilation & expulsion of foetus, placenta & membranes - is dependent on 4Ps
What is does power involve?
Fundal dominance
–> greater intensity of uterine contractions in fundus (at the point called fundal dominance) relative to those in mid or lower portions of uterus
–> uterine contractions start at fundus (near cornua) of uterus & spread outwards & downwards
-Upper & lower poles of uterus acting together - contraction & retraction of upper pole & dilatation of lower pole = allows expulsion of foetus (known as polarity)
-After each contraction - muscle fibres retain some shortening of contraction = retraction
*Forces to expel foetus
*Contractions = involuntary (dilates & effaces cervix) - but is also voluntary bearing down = maternal effort kicks in after involuntary
–> as descending foetus puts pressure on vaginal wall & rectum - triggering urge to push
-Function of uterine contraction = effacement (softening, thinning & shortening of cervix) & dilation
-In early labour
-> contractions 15-20 mins apart & last <30 secs
-In established/active labour
-> contractions 3-4:10 mins & last 50-60 secs
What does passage involve?
Passageway:
*Pelvis
*Soft tissue:
-Lower uterine segment
-Cervix
-Vagina
-Perineum
–> this soft tissue must stretch to allow passage
When baby is in pelvis - foetal skull should through widest portions at each level:
-Transverse plane - in pelvic inlet
-Anterior-posterior plane - in mid pelvis & pelvic outlet
-Coccyx has some mobility = increases space in outlet
-Progesterone & relaxin help facilitate softening & increase the elasticity of muscles & ligaments
Boundaries of pelvic brim?
-Anteriorly -> by pubic symphysis
-Posteriorly -> by promontory of sacrum
-Laterally -> by iliopectineal lines
What does passenger involve - state!?
-Lie
-Presentation
-Presenting part
-Attitude
-Denominator
-Position
What is lie (passenger)?
Relationship of foetal long axis to that of uterus
-Longitudinal (99% at term)
-Transverse
-Oblique
What can the different presenting parts be (passenger)?
-Cephalic
-Breech (complete, footling, frank)
-Shoulder
-Compound e.g., hand
What is presenting part (passenger)?
Part of foetus laying at pelvic brim or in lower pole of uterus
-Cephalic
-Breech
-Face
-Brow
-Shoulder
What is attitude (passenger)?
Relationship of foetal head & limbs to its body
-Fully flexed
-Deflexed
-Partially
-Completely extended
What is denominator (passenger)?
Part of presentation used when referring to foetal position in relation to:
-Pelvis. occiput
-Sacrum = breech
-Mentum = face
-Acromion = shoulder
-Frontal eminence = brow
What is position (passenger)?
Relationship of denominator to 6 key points on maternal pelvic brim:
Occipital anterior
-Right occipito-anterior
-Right occipito-transverse
-Right occipito-posterior
Occipito posterior
-Left occipito-anterior
-Left occipito-transverse
-Left occipito-posterior
What is engagement?
When widest transverse diameter of presenting part has passed through pelvic inlet
–> when Biparietal plane of foetal has passed plane of pelvic brim - is engaged
-Biparietal diameter (9.5 cm) is widest diameter/greatest horizontal plane
-Measured in 1/5s
–> when 2/5s palpable = not engaged yet!
-Engagement of foetal head occurs from 38 weeks gestation
What does psyche involve?
-Progress of labour & birth can be adversely affected maternal fear & tension -> emotional disturbances in labour can temporarily stop contractions e.g., coming into hospital, change in staff
-Norepinephrine & epinephrine may stimulate alpha & beta recs of myometrium & interfere with rhythmic nature of labour
-Anxiety can increase pain perception & lead to increased need for analgesia & anaesthesia
Potential complications in labour?
-Failure to progress
-Foetal distress - necessitating immediate delivery - blood PH
-Sepsis
-Shoulder dystocia
-Retained placenta
-Uterine inversion
-Haemorrhage (4Ts - tone, trauma, tissue & thrombin)
-Perineal trauma
Trauma - episiotomy:
1st - perineal skin
2nd - perineal body muscles & skin
3rd - EAS & IAS
4th - rectal mucosa
Unicef x3 themes regarding breastfeeding?
-Constituents of human milk – including colostrum & mature breastmilk
-Protective & developmental functions – including the effect on immune system, microbiome, developmental programming and growth
-Role of human milk & breastfeeding in promoting & protecting public health
Structure of lactating breast?
External changes:
-Become bigger
-Areola & nipple may darken
-Montgomery’s tubercles appear on areola to secrete an antiseptic sebum to lubricate area
-Sebum secretes a scent to entice baby to begin to search in area for 1st feed
-Fair skinned women - may see ‘marbling’ as blood supply to breast increases
-Tender in early stages of pregnancy due to ductal growth
-May produce colostrum from ~16 weeks gestation
-During pregnancy ductal system & alveolus develop under influence of oestrogen, progesterone & human placental lactogen
-In each alveolar sac = 1000s of lactocytes (produce milk)
-Myoepithelial cells (surround alveolus & ductal system) - muscle cells - help squeeze milk down ducts to openings in nipple
What is the prolactin receptor theory?
-Alveolus = made of many lactocytes surrounded by orange muscle (myoepithelial) cells
-On lactocyte cell walls = prolactin recs
-Prolactin levels in blood - rise in response to touch & suckling by baby
-More circulating prolactin (due to more frequent contact & suckling) = greater no. of lactocytes are activated
More early, frequent surges of prolactin = greater no. of recs are primed (= max. no of recs) -> meaning max. no.s of functioning lactocytes from that point onwards & max. triggering of mothering response
–> more recs = more functioning lactocytes = more milk produced
How do prolactin & oxytocin work together?
-Chef = (prolactin) -> makes the milk
-Waiter (oxytocin) -> delivers the milk
*Circulating oxytocin acts on muscle cells myoepithelial cells - surround lactocytes) to release milk from the lactocytes
What is feedback inhibitor of lactation (FIL)?
-Circulating prolactin in blood controls milk production
-Prolactin vols can be irregular at first - so mothers may experience full breasts & leaking as supply & demand establishes
-As breasts become full by:
*ineffective milk removal (or)
*long spacing of feeds
–> protein in milk - FIL slows synthesis by signalling to cells to stop production
-This down regulation (reduced milk production) = also caused by pressure in full breast flattening & expanding cells & recs -> so is difficult for prolactin to attach to & enter cells.
Components of formula VS human milk?
Benefits of breastfeeding?
Women who breast feed longer have lower rates of:
-Type 2 diabetes
-High BP
-Heart disease
-Provides immune protection
-Contraceptive benefit
-Reduces the risk of breast & ovarian cancer
-Cheaper
-More convenient
-Prevents the proliferation of E. coli
-Lactoferrin in breast milk binds iron, E. coli is an iron dependent organism
-Encourages colonisation of gut by non pathogenic flora
-IG are present
-Reduces allergy & atopy (IgA) and diarrhoea
-Bactericidal enzymes are present
Disadvantages of breastfeeding?
How can views of breastfeeding be protected?
