What are counted as term deliveries?
Deliveries between 37 and 41 Weeks of Pregnancy
When do post-term deliveries take place?
After 42 Weeks of pregnancy
When do pre-term deliveries take place?
How can you differentiate?
Pre-term= deliveries between 22-37 weeks
- Extremely preterm
- 22-28 weeks
- Very preterm
- 28-32 weeks
- Moderate to late preterm
- 32-36 weeks
What are misscarriages?
How can you distinguish between them?
Miscarriage: Less than 22 weeks (non viable infant delivered).
- Early miscarriage
- First trimester (common, often due to problems in anchoring and vascular formation)
- Late miscarriage
- Second trimester less than 22 weeks
What are the key tissues involved in Labour?
- The mxometrium
- Cervix and the
- Fetal membranes
What is the clinical definition of labour?
Fundally dominant contractions
- coordinated contraction of the myometrium combined with
Cervical ripening & effacement
- change in cervical structure –> softens
Also involved:
- Rupture of fetal membranes
- Delivery of infant
- Delivery of placenta
What is the latent stage (of labour?)
It is the stage about 8 weeks prior to delivery myometrial remoddeling (+ practice contractions) happen
What happens in the three stages of labour?
How long do they take?
- Stage 1= Contractions, cervical changes (usually rupture of fetal membranes) (variable, many hours)
- Stage 2= Baby delivered (hours)
- Stage 3= delivery of placenta (around 30 min)
What are factors that might trigger preterm initiation of labour?
- Intrauterine infection
- activation of inflammatory cascade (NF-kß)
- Intrauterine bleeding
- Multiple pregnancy
- Stress (maternal)
- Others
Which factors initiate full term labour in humans?
–Not really sure!!!
–Estrogens; low progesterone?; CRH?; oxytocin?
What happens during cervical ripening and effacement in labour?
It is an inflammatory change!!
- Change from rigid to flexible structure
- Remodelling (loss) of extracellular matrix
- Recruitment of leukocytes (neutrophils)
- Inflammatory process
- Prostaglandin E2, interleukin-8
- Local (paracrine) change in IL-8
Explain the key characteristics and that happen to the endometrium during labour and the most important mediators
- Fundal dominance
- Increased co-ordination and power of contractions
- Key mediators
- Prostaglandin F2a (E2) levels increased from fetal membranes
- Oxytocin receptor increased
- Contraction associated proteins
What is involution?
What is its significance?
It is tue poweful contraction of the uterus after delivery of the placenta
–> prevents mother from bleeding to death
What happens to the fetal membranes during labour?
What are the key mediators?
Also Inflammatory
- Rupture of fetal membranes
- Loss of strength due to changes in amnion basement component
- Inflammatory changes, leukocyte recruitment
- Modest in normal labour, exacerbated in preterm labour
- Increased levels and activity of MMPs (matrix Metalloproteases)
- PGs and interleukins
What is the role of NF-kß in labour?
How is it activated?
Seems to be activated by many initiators of laborur
And is the main regulator, driver of labour
- +ve feedback loop (causes inflammation and inflammation causes expression of NF-kß)
*
What does activation of NF-kB lead to?
It is a Transcription factor
- binds to promoters of pro-labour gene
- upregulation of these genes and driving of inflammation leading to expression of
- COX-2 (prostaglandins - PGs),
- IL-8, IL-1b,
- MMPs,
- Oxytocin and PG
- contraction-associated proteins
- upregulation of these genes and driving of inflammation leading to expression of
Explain the role of Platelet-activating factor
It is a fetal signal of maturity that might lead to initiation of Labour (via upregulation of inflammatory processes)
- Part of lung surfactant
- Produced by maturing lung, before birth
- Increased levels before birth
Explain the role of CRH in labour
CRH up-regulate inflammatory pathways in fetal membranes via stimmulation of Progesterones and IL
- Maternal CRH causes production of fetal corticosteroids leading to
- +ve feedback of CRH production in the placenta
- Production of Estrogens (leading to further modulation e.g. in oxytocin receptors)
Explain the role of Progesterone in labour
Thought to possibel initiate labour
- High levels are needed to keep pregnancy
- High levels of Progesterone Receptors inhibit NF-kB during pregnancy leading to
- lower levels of inflammation
- At term: less of Progesterone Receptors B (that are the main mediators of levels of progesterone in comparison to PR A can mediate the reponse less)
- Activation of NF-kB
Which biochemical pathways of labour are affected by progesterone?
Via the increase expression of NF-kB
Explain how examination of the cervix is used to assess the progress of labour
- The cervix must be 10 cm dilated and 100% effaced (thinned out) for delivery (can be felt)
