physiology of birth and lactation

how long is normal pregnancy

when is a baby premature and postmature

when is it considered labour

Normal pregnancy = 40 wks  

Term = 37-40 wks  

Premature = less than 37/40 wks  

Postmature = more than 41/40 wks  

 

Labour > 24/40 wks  

define:

• nulliparous

• primiparous

• multiparous

• grand multiparous

• gravidity

• parity

 

Nulliparous: never given birth  

Primiparous: giving birth for the first time  

Multiparous: birthed more than one child  

Grand multiparous: delivery of 5^th or more child  

 

Gravidity: number of times pregnant  

Parity: number of babies born over 24 weeks  

what is

G1P1

G2P1

G1P2

G1P0+

G2P0+2

G2P2-1

G1P1= pregnant 1 born 1

G2P1= pregnant1 born twins

G1P2 = pregnant now and previously once

G1P0+ = pregnant once, miscarriage

G2P0+2= both times pregnant, miscarriage

G2P2-1 = pregnant 2 birthed 2 but one was stillborn

what is parturition

labour

what is effacement of cervix

• Softening, thinning, shortening of cervix, % 

labour

• what is it

• what are the measurements

 (4cm+) 

Diagnosis: painful uterine contractions which accompany dilation and effacement of the cervix  

what are the 2 phases of labour

latent phase and active phase

what is the latent phase of labour + measurements

• Painful contractions accompanied by thinning and opening of the cervix  

• Up to 4 cm  

what are the 3 stages of active phase of labour

1^st stage  

• Regular uterine contractions to full dilation (4-10cm) 

2^nd stage (passive and active phase) 

• Passive: Descent of presenting part (1hr) 

• Active: active pushing once fully dilated with uterine contractions  

• From full dilation to delivery of foetus  

3^rd stage  

• Delivery of placenta  

what is it called when the perineum is cut for labour

episiotomy

what hormones help with onset of labour

• Maternal  

• Progesterone withdrawal  

• Oxytocin stimulation  

• Prostaglandins  

• Serotonin  

what are the mechanics of labour, the three Ps

power, passage and passenger

what power drives labour 2

Uterine activity  

• Regular uterine contractions  

• 2-3 mins  

• Lasts 45-60 seconds 

Maternal effort  

• Second stage, co-ordinated pushing  

describe the 3 layers of muscle of the uterus

Layers: outer longitudinal, middle crossed, inner circular 

• All work together to expel baby  

• OL, MC, IC 

whats the avg foetal size

foetal lie

presentation

position

attitude

Passenger  

• Foetal size avg 3.35kg (7lb 6oz) 

Lie – vertical/ upside down  

Presentation – cephalic  

Position – OA (OA occipital anterior – position) 

Attitude – flexed/vertex 

what is breech position

face side up

what does vertex foetal attitude mean

(chin almost in contact with chest)

delivery of the head DFICERE

• dont forget i can easily ruin events

• descent

• flexion

• internal rotation

• crowning

• extension

• restitution

• expulsion!

describe descent

• Biparietal diameter (BPD) passes through pelvic inlet  

• Pressure of amniotic fluid  

• Direct pressure of fundus on foetus with contractions  

• Maternal abdominal muscles  

• Extension and straightening of body  

describe flexion

• Head descends, meeting resistance from soft tissues  

• Causes further flexion  

• Chin brought closer to foetal chest  

describe internal rotation

Occurs once head reaches pelvic floor

describe crowning

• Appearance of foetal scalp at vaginal orifice in childbirth  

describe extension

• Foetal chin moves away from chest  

• Neck extends  

describe restitution - external rotation of the head

• Realignment of head with shoulders  

• Head shoulders trunk  

describe expulsion

• Delivery of head followed by delivery of shoulders in next contraction  

what happens during the third stage of labour

• how long

• 3 management techniques

• Expulsion of placenta and membranes  

• 10-30mins  

• Management: 

• Complete delivery of after birth (placenta and membranes) 

• Prevention of postpartum haemorrhage PPH 

• Prevention of acute inversion of uterus  

physiological part of delivering placenta

• duration

• relies on which hormone

• risk

• what helps delivery

• Max 1hr  

• Relies on intrinsic oxytocin production to encourage separation of placenta and membranes  

• Low risk  

• Maternal pushing, gravity, breastfeeding help deliver  

active phase in pushing placenta

• duration

• hormone

• risk of PPH

• what is CCT

• Max 30mins  

• Dose of IM oxytocin given at delivery of shoulders  

• Reduces risk of PPH by 60% 

• Placenta delivered by controlled cord traction CCT  

what are the different types of perineal tears

1st degree - vaginal mucosa torn

2nd degree - perineal muscles torn

3rd degree - anal sphincter torn

4th degree - rectum torn

lactation

• which glands are responsible in the breasts

• which system undergoes hypertrophy

• what does progesterone do

Mammary glands embedded in breasts: 

• Contain lobes made of alveoli  

• Hypertrophy of ductular-lobular-alveolar system  

• Progesterone converts duct epithelium into milk secreting lactocytes  

during pregnancy, what does OE and PG do in lactation

• Oestrogen and progesterone in pregnancy inhibit milk production  

what is the difference in breast tissue in the 1st 20weeks compared to the third trimester

In first 20 wks: 

• Ducts branch and extend  

• Lobes and alveoli proliferate and expand  

Third trimester: 

• Lobe hypertrophy (cells double in size) 

• Epithelial cells converted to lactocytes  

 

what are the 3 stages of lactation called

lactogenesis 1,2,3

explain what happens in lactogenesis 1,2,3

Lactogenesis 1: 

• Breast development and colostrum production from approx, 16wks  

• Bigger breasts, darker areola, leaking – normal during pregnancy  

Lactogenesis 2: 

• Milk secretion occurring entre 32-96 hours after birth  

Lactogenesis 3: 

• Maintenance of milk production  

which hormone stimulates milk production

prolactin

what is prolactin release stimulated by

baby sucking on the breast

how does oxytocin cause the release of milk

Oxytocin causes release of milk by stimulating contraction of myoepithelial cells around alveolae

what is the baby friendly initiative, 3 stages

S1: guidelines and policies, no promotion of breastmilk substitutes

S2: empower staff to support parents w/ infant feeding journey

S3: allow change for different needs of families

what are the 3 stages of breast milk + duration

• C + composition

• TM

• MM

Colostrum 

• From birth – 3days  

• Rich in immunoglobins IgA 

• Gives passive immunity, supports GIT  

Transitional milk 

• 3 – 14days  

Mature milk  

• From 2 – 4weeks  

why can BM change colours

• Will change colour based on different circumstances  

• If baby is ill, will change to give immunoglobins to help protect the baby  

what helps with bonding

• benefits of breast feeding

• Encourage skin-to-skin contact, helps with bonding  

• Eye contact when breastfeeding  

• Dont separate mum and baby unless necessary  

• BF protects children from vast range of illness  

• Protects mothers from ovarian, breast cancer, heart disease  

• Cost efficient