Labour Flashcards

1
Q

What is term delivery?

A

37-41 weeks gestational age (since LMP)

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2
Q

What is birth?

A

The final phase of pregnancy

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3
Q

What is pre-term delivery?

A

22-37 weeks gestational age (since LMP)

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4
Q

What is very pre-term delivery?

A

28-32 weeks gestational age (since LMP)

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5
Q

What are the key tissues involved in labour?

A

Cervix
Myometrium
Foetal membranes

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6
Q

Summarise the main biochemical processes of labour (endocrine, inflamm)

A

Foetal membranes:

  • Inflammatory process
  • PGs, ILs, MMPs
  • Waters breaking

Cervix: dilation (effacement, ripening)
- IL-8, PGE2, MMPs

Myometrium:

  • Increased contraction associated proteins
  • Increased oxytocin receptors
  • PGF2a (E2) levels increased from foetal membranes
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7
Q

How is the cervix assessed before the onset of labour?

A

Bishop’s score

  • Pre-labour scoring system to assist in predicting whether induction of labour will be required
  • Also used to assess likelihood of spontaneous preterm delivery

Total score calculated by assessing 5 components on manual vaginal examination:

  • Cervical dilation in cm
  • Cervical effacement as %
  • Cervical consistency
  • Cervical position
  • Foetal station - position of foetal head in relation to pelvic bones

Call PEDS For Parturition! = Cervical Position, Effacement, Dilation, Softness; Foetal Station

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8
Q

What occurs during cervical ripening?

A
  • Cervix becomes softer + more flexible
  • Change from rigid to flexible structure
  • Remodelling (loss) of ECM
  • Recruitment of leukocytes (neutrophils)
  • Inflammatory process - PGE2, IL-8
  • Paracrine (local) change in IL-8
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9
Q

What are the 3 stages of labour?

A
  1. Cervical dilation - effacement + ripening
  2. Expulsion of infant
  3. Afterbirth - delivery of placenta
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10
Q

What happens in the first stage of labour?

A
  • Cervix is undilated - too narrow
  • High conc of oxytocin being released from neurohypophysis causing uterine contractions
  • Contractions cause membranes surrounding foetus to release PGs that soften up cervix + cause more uterine contractions
  • Positive feedback loop between uterine contractions + PG release = true labour
  • Sides of uterus contract upwards, which pulls cervix thinner and causes it to open up
  • Contractions push foetus against cervix –> dilates even more
  • Relaxin released from placenta dilates cervix
  • Mucus plug (seals opening of cervix during pregnancy) comes out and discharged out of vagina
  • Can happen up to 2 days before to during labour
  • Amniotic sac ruptures (foetal membranes)
  • When cervix dilates to 4cm –> body moves into active labour –> stronger + closer together contractions
  • Max diameter - 10cm –> urge to push –> 2nd stage of labour
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11
Q

What triggers relaxin release from the placenta?

A
  • Progesterone starts to drop off at 37 weeks
  • Higher oestrone:progesterone ration caused increased uterine contractions (false labour)
  • Placenta releases relaxin
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12
Q

What does relaxin do?

A
  • Relaxes pelvic ligaments so pelvic bones can part to support enlarging uterus
  • Opens up pelvic outlet by loosening pubic symphysis
  • Helps dilate cervix during labour
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13
Q

What happens in the 2nd stage of labour?

A

Expulsion on infant

  • Starts when foetal head enters birth canal
  • Uterus continues to rhythmically contract to push baby out
  • Skull bones of newborn aren’t fully fused - slide over top of each other and compress each other enough to get skull thr birth canal
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14
Q

What happens in the 3rdd stage of labour?

A
  • Afterbirth
  • Delivery of placenta + associated membranes
  • Uterus continues to contract after abby delivered
  • Causes placenta to detach from walls of uterus and eject out of vagina
  • Uterus continues to contract to help uterus to return to pre-gestation size = involution
  • Allows abdominal organs to return to original positions
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15
Q

What happens in the 3rdd stage of labour?

A
  • Afterbirth
  • Delivery of placenta + associated membranes
  • Uterus continues to contract after abby delivered
  • Causes placenta to detach from walls of uterus and eject out of vagina
  • Uterus continues to contract to help uterus to return to pre-gestation size = involution
  • Allows abdominal organs to return to original positions
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16
Q

What occurs during cervical dilatation?

A
  • Cervix becomes thinner + wider
17
Q

What happens during the rupture of foetal membranes?

A
  • Loss of strength due to changes to amnion basement component
  • Inflamm changes, leukocyte recruitment
  • Increased levels and activity of MMPs
  • Inflamm process in foetal membranes
18
Q

What is cervical effacement?

A

Thinning of cervix