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Labour, delivery and birth

dilation of cervical canal

allows passage of foetus from uterus through ******

Myometrial contractions in uterus must be strong enough to push baby out

During first two trimesters uterine muscle remains quiet

Inhibitory effects of high progesterone 

3rd trimester - Braxton - Hicks contractions

increasing strength and frquency 

may cause false labour

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End of Pregnancy

cervical softening/ripening

connective fibres have dissociated

caused by peptide hormone relaxin

relaxes pelvic bones

foetus shifts downwards(dropping)

baby orientated so head is down in contact with cervix

compare with breech birth

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Onset of labour

Coordinated uterine contractions

Increased frequency and discomfort

force foetus agaisnt cervix

baby pushes through birth canal

endocrine factors determine inset of labour -- placental clock

Contraction begins at top of uterus 

cervical stretch receptors - stimulate oxytoxin - more powerful contraction

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Stages of labour - membranes rupture (water breaks)

cervix dilates 10 cm for baby flows

If not the head - medical assistance may be required

Birth of the Baby - 2nd stage once cervical dilation is complete

Infant moves through cervix and ****** 

******l stretch receptors activate neural reflex

abdominal wall contracts in sync with uterus

Mother can assist in 'push'

Voluntary contraction of abdominal muscles

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Placenta delivery and Involution

caused by uterine contraction

Placenta separates from myometrium

the expelled through ****** 'AFTERBIRTH'

Shirtests stage is 15-30 mins after birth

constructs uterine vessels 

prevents heammorage

Involution - occurs after delivery

Uterus shrinks 

If material not dispelled it disintegrates 

results in ******l discharge 

continous through 3-6 months 

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