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RDA - reproduction, development and aging > human labour and delivery > Flashcards

human labour and delivery Flashcards

1
Q

define miscarriage *

A

delivery of a non-viable infant <23wks of gestation

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2
Q

why do miscarriages happen at end of trimester 1 *

A

there is a switch in the contact of the placenta - blood that was being kept away from the placenta can now access it

therefore if the placenta is not anchored properly it cant cope with the pressure and is dislodged = miscarriage

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3
Q

what is preterm delivery *

A

23-37 weeks of gestation

this is because difficult to stop labour once it has started so can be preterm labour

or preterm caesarean - when baby/mum medically comprimised eg by high BP - preterm caesarian can be fine but there can be risks

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4
Q

what is the size of a baby at term

A

head size of adult hand

should fit on forearm

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5
Q

what is term delivery *

A

delivery at 27-41 wks - either by labour or elective caesarian

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6
Q

what is the result of a preterm delivery *

A

all the structural features are there

but some features might not have developed properly

small

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7
Q

define labour *

A

fundally dominant contractions - myometrium was relaxed in pregancy to allow expansion - changes to contracting so that the baby is pushed out

cervical ripening and effacement - change in tissue structure from firm to soft and flexible - become open space so that the baby can get out

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8
Q

summarise the process of labour *

A

it is independant of gestational age

  • cervical ripening and efficacement (increasing)
  • co-ordinated myometrial contractions (increasing)
  • rupture of fetal membranes - amniotic fluid leaks - this is water breaking
  • delivery of infant
  • delivery of placenta
  • contraction of the uterus
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9
Q

describe the stages in labour *

A

pregnancy is having 39weeks not in labour

latent stage is 8wks - uterus beginning to change - parts contract and then relax - otherwise rapid contraction wouldnt work at term

labour - 12-48hrs - increasing contractions

  • phase 1 is many hours (longer in 1st pregnancy) - beginning of onst of contractions through the period of dilation of the os uteri, rupture of fetal membrane, changes to uterus and cervix
  • phase 2 is hours - contractions and cervical changes
  • phase 3 - 30mins - baby delivered and placenta and fetal membrane delivered
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10
Q

what can slow down delivery *

A

if baby is bottom 1st

emergancy delivery is needed

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11
Q

what causes initiation of labour at term *

A

not sure

eostrogen

perhaps low progesterone, or CRH or oxytocin

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12
Q

what causes initiation of labour preterm *

A

intrauterine infection

intrauterine bleeding

multiple pregnancy

stress - maternal

other fators

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13
Q

describe cervical ripening and effacement in pregnancy *

A

change from rigid to flecible structure

remodelling (loss) of ECM

recruitment of leukocytes (neutrophils)

it is an inflammatory process involving PGE2, IL-8, and a local (paracrine) change in IL-8

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14
Q

describe the coordinated myometrial contractions in labour *

A

driven inside uterus

fundal dominance

there is increased coordination and power of contractions

inflammatory cascade - key mediators

  • PGF2alpha (E2) levels increased from fetal membranes
  • oxytocin receptor increased
  • contraction associated proteins
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15
Q

describe the rupture of fetal membranes in labour *

A

loss of strength due to changes in amnoin basement component

inflammatory changes and leukocyte recruitment - this is modest in normal labour and exacerbated in preterm

there is inreased activity of MMPs

inflammatory process in fetal membranes

interleukins and prostaglandins are involved

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16
Q

describe the role of NFKb in labour *

A

it is a pro-inflammatory transcription factor - it controls the production of endpoints:

  • COX-2
  • cPLA2
  • IL1B
  • IL6
  • IL8

IL-1b especially, is inviolved in increasing levels of NFKb - it is a feedforward mechanism

this is what makes it difficult to stop labour once it has started

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17
Q

summarise the inflammatory cascade that is labour *

A

many initiators cause production of NFKb

NFKb is a transcription factor upregulating many genes than are mostly inflammatory

  • COX2
  • PGs
  • IL8
  • IL1B
  • MMPs
  • oxytocin receptor
  • PG receptors
  • contraction associated proteins

these drive the changes that occur in labour

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18
Q

what is the supporting evidence for the fact that NFKb is a key part of labour *

A

almost all pro-labour genes have NFKb binding domains in their promotors - ie NFKb upregulates all the factors involved in labour, in the same way at the same time

modification of the NFKb sites in the promotor sequence leads to loss of expression of cells or in expression vectors

infection (ie intrauterine infection/UTI) drives up inflammation and is very linked to preterm labour

19
Q

describe PGE2 synthesis in vitro with addition of NFKb *

A

when tissues in vitro - they produce some PGE2, this is increased when NFKb is added

however when fetal membrane at term is not in labour - there is no increase in PGE2 production when NFKb is added - it is already at max production - the tissues have biochemically switched into labour

20
Q

what is the hypothesis for the control of term labour *

A

CRH and PAF are the key drivers of the biochemical change in labour

CRH rises in the last 3 weeks of labour

COX-2 increases in amnion and chroion-decidus tissue in last 3 weeks of pregnancy - COX2 is what makes the PGs that drives the endometrium and cervix

PAF (platelet activating factor) is part of lung surfactant which is produced by the maturing lung before birth - lung is last tissue to mature - the PAF signal is involved in initiation of labour and its levels in amniotic fluid rise near term - surfactant is a fetal signal of maturity

CRF and PAF stimulate production of PGs and COX-2

also upregulate production of IL-1B which is a pro-inflammatory cytokine and drives production fo the molecules needed for labour

21
Q

summarise the overall hypothesis for partuition (labour) *

A

CRH is made in the placenta - this stimulates the cascade that occurs in the fetal membrane and goes into the umbilcal cord

it works on the pituitary gland of the fetus causing release of ACTH which works on adrenal gland = cortisol production

cortisol goes through the umbilical cord to the placenta and upregulates CRH production - feedforward mechanism

CRH activates labour by causing production of IL and PGs

adrenal glands also produce steroids that mature lungs and cause production of PAF that contributes to labour

adrenal glands also make the precurser to oestrogen (DHEA) - oestrogen causes th myometrium to contract

22
Q

what are things that follow from this theory of labour *

A

anything that increases CRH may predispose to labour - stress, multiple infants

anuting that increases muscle contraction may predispose to labour - excess stretch of uterus

anything that activates inflammatory cascades may predispose to labour

this all applies to preterm labour - intrauterine infection, bleeding, twins

23
Q

what is the role of progesterone in pregnancy *

A

it is needed to sustain preg - if block the prog receptors = loss

the prog levels stay high until after the delivery of the placenta

in pregnancy have high PR which binds to NFKb - means that progesterone can act, also that NFKb is inactive

in labour there is an increase in NFKb and a decrease in progesterone receptor

therefore there is more NFKb present to act and drive labour

PAF, CRP and hence COX-2 are affected by progesterone

24
Q

describe the progesterone receptor *

A

PR-B mediates the effects of progesterone via gene expression

PR-A is less able to mediate these effecys

ratio of PRA:PRB increases at term - therefore there is ‘functional progesterone withdrawal’ - there is still progesterone just no PR to mediate the effects

25
Q

what is the difference between term and preterm labour *

A

the initiation factors

26
Q

why must the uterus contract at the end of pregnancy *

A

because the vessels are wide and have no sm - meaning they cant contract so you would lose a lot of blood

therefore uterus contracts to shut of the vessels

if any placenta is left in the uterus, it holds open the bv so needs to be removed

27
Q

post-term *

A

>42 weeks

28
Q

pre-term *

A

22-37

29
Q

extremely pre-term

A

22-28

30
Q

very preterm *

A

28-32

31
Q

moderate to late preterm *

A

32-36weeks

32
Q

miscarriage *

A

<22wks

33
Q

early miscarriage *

A

1st trimester

34
Q

late miscarriage *

A

second trimester in <22wks

35
Q

what is the main cause for early miscarriage *

A

major developmental complications - so pregnancy is not viable for >than a few weeks after conception

36
Q

describe contraction of the uterus*

A

Myometrium is a layer of muscle

Driven to contract by increased Ca conc

Driven by PG F2a And oxytocin

Involution after delivery is driven by increase in oxytocin level

37
Q

definition of labour

A

the process of expulsion of the fetus and placenta from the uterus

38
Q

describe delivery of the placenta *

A

within 30mins of birth

accompanied with very powerful contractions of the uterus = rapid decrease in size - this is involution

it stops blood flow through the spiral arteries

linked to increased levels of oxytocin - if doesnt occur spontaneously an injection of oxytocin/other uterine contraction can be given

39
Q

describe cervical ripening and dilation *

A

ripening - becoming softer and more flexible

dilation - becoming thinner and stretced sideways

requires remodelling of ECM - accelarated by increasing pressure of the fetal head on cervix caused by increasing strength and decreasing gaps between myometrial contractions

factors involved - PGE2, IL-8, MMPs

40
Q

When can pregnancy be dangerous to the mother *

A

when mother is in poor health at beginning eg due to malnutrition - the additional strain of pregnancy might have a severe impact

pre-eclampsia affects the maternal vascular system which can pose health threats to mother

labour

41
Q

causes of extremely preterm labour *

A

intrauterine infection

bleeding

42
Q

why is the brain at risk in preterm labours *

A

brain suseptible to inflammatory process - preterm labour can be initiated by intrauterine infection

43
Q

define how the cervix is assessed before the onset of labour *

A

only done when the cervix is sterile

feel position, consistency, effacement and dilation of the cervix

if the membranes are in tact/ruptured and if ruptured what is the colour of the amniotic fluid

assess the position of the fetus

44
Q

summarise how examination of the cervix is used to assess the progress of labour *

A

assessed by the rate of cervical diliation and descent of the presenting part

assessed by vaginal examination at the beginning and then every 3 hours of labour

expected progress of 1cm/hr identifies those progressing slowly - if 2 hours slower then action is taken - artificial ROM or oxytocin infusion

descent of the head is charted

RDA - reproduction, development and aging (10 decks)

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