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Which hormones are actively involved in transforming a pregnancy into the labour phase?

Progesterone levels decrease and oxytocin increases which increase uterine contractions
Prostaglandin levels increase which lead to cervical ripening and increase uterine contractions
Oestrogen and relaxin also contribute to this


When is a foetus considered mature?

Maintain an independent existence outside the uterus
Breathe / maintain oxygenation
Feed / Maintain blood sugars
Maintain body temperature


When is a foetus considered viable?

Can survive extra-uterine
Usually 23-24 weeks depending on neonatal intensive care facilities


When is a foetus considered term?

Gestational age
37 completed weeks till 42 weeks


When is a foetus considered pre term?

Earlier than 37 completed weeks and after accepted age of viability (23-24 weeks)


When is a foetus considered post mature?

After 42 weeks


What processes have to occur in the process of parturition?

Cervical ripening / effacement
Cervical dilatation
Uterine contractions
Foetal membrane rupture


What is cervical effacement?

Cervix shortens and thins


What is a bloody show?

Mucus plug loosened and released from cervix as it starts to efface


What is the latent phase of labour?

Once cervix effacement starts to dilation of 4cm and regular contractions have begun


What factors contribute to cervical ripening?

Prostaglandin E2 (PGE2) and F2-alpha
Hyaluronic acid
Chemotaxis for leukocytes, causes increased collagen degradation
Stimulation of interleukin (IL)–8 release
Activity of matrix metalloproteinases 2 and 9
Cervical collagenase and elastase


Why can infection or inflammation lead to pre term labour?

Cytokines: interleukins 1 and 6 released as inflammatory response can trigger the process of cervical ripening and uterine contractions as they lead to the production of prostaglandins E2 and F2a


What are indications for inducing labour using prostaglandins?

Prolonged pregnancy
Pre labour rupture of membranes
Concerns about health of mother: pre eclampsia
Concerns about health of baby: poor growth


What can be used to induce labour?

Prostaglandin E2
Propess and cervidil: controlled release vaginal insert
Prostin and glandin: vaginal suppositories


What are the names of the foetal membranes?

Chorion: outermost membrane, contributes to placenta formation
Amnion: when first formed, closely covers embryo, fills with amniotic fluid to become protective sac


What cellular changes occur to allow growth of the uterus?

Smooth muscle hyperplasia and hypertrophy


When is the first trimester?

0-12 weeks


When is the second trimester?

13-28 weeks


When is the third trimester?

29-40 weeks


What are the layers of the uterus?

Endometrium: highly vascular mucosa, stratum functionalis (shed during menstruation), stratum basalis (permanent, gives rise to new functionalis after each cycle)
Myometrium: three layers of muscle
Perimetrium/serosa: visceral peritoneum


What happens to the Myometrium prior to parturition?

Increased expression of contraction-associated proteins,
including oxytocin receptors, connexin-43, and prostaglandin F2alpha receptors
Down-regulation of the nitric oxide (NO) pathway and other
vasorelaxing peptides


What happens to the myometrium during labour?

Prostaglandins and oxytocin act in synergy to trigger contractility through an increase in intracellular Ca2+ concentration


What percentage of deliveries are pre term?



What factors could cause pre term labour?

Increasing maternal age, stress (domestic abuse)
Pre term rupture of membranes: infection, smoking, drug use, previous PROM, polyhydramnios, multiple gestation, amniocentesis, poor nutrition, cervical insufficiency, low SES, underweight
Pre term contractions
Cervical insufficiency: previous cervical biopsy, uterine abnormalities, trauma to cervix


What are tocolytics? Give examples

Used to suppress premature labour, buy time for administration of betamethasone
Terbutaline/salbutamol: B2 agonist
Nifedipine: ca channel blocker
Atosiban: oxytocin antagonist
Indomethacin: NSAID
Magnesium sulfate: myosin light chain inhibitor, reduce risk of cerebral palsy


What is Oligohydramnios? What increases the risk of this?

Foetal chromosomal abnormalities
Intra uterine infections
PG inhibitors, ACE inhibitors
Obstruction of foetal urinary tract
Intra uterine growth restriction
Amnion nodosum: failure of secretion by amnion cells covering placenta
Post maturity


What is polyhydramnios? What increases the risk?

Twins/ multiple gestation
Gestational diabetes
Gastrointestinal atresia of foetus
Rhesus disease in mother
Chromosomal abnormality of foetus
Hydrous fetalis: fluid build up in foetus' abdomen or thorax


What factors can be used to predict the risk of pre term labour?

Past obstetric history
Cervical length
Bacterial vaginosis
Cervical factors: Fetal fibronectin, actim partus


What is foetal fibronectin?

Found at interface of chorion and decidua: "glue" that binds foetal sac to uterine lining
Leaks info vagina if pre term delivery is likely to occur so can be measured as a screening test


What is actim partus?

Phosphorylated insulin like growth factor binding protein detected in cervical samples
Has high negative predictive value - negative result, labour will not begin in next 7 days so can be sent home with confidence