Repro 10.1 partuition. Flashcards Preview

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Define partuition:

'the transition from the pregnant state to the none pregnant state at the end of gestation'


Define labour in medical terms?

'describes partuition when both the cervix and uterus have been remodelled'


After what time is expulsion of products of conception known as partuition?

24 weeks


What is the medical term for expulsion of the products of conception before 24 weeks?

spontaneous abortion

(lay people- miscarriage)


What does pre-term mean?

a foetus born after 24 weeks (but before 36)


What does 'term' mean, in terms of partuition?

partuition between 37-42 weeks.


What does 'post term' mean?

Partuition after 42 weeks.


Why is a baby born a long time (weeks) after the due date dangerous?

It can die in utero (placenta can't manage for the bigger needs, and is only supposed to last for 38 weeks)

Can cause haemorrhage and death of the mother.


Broadly, what are the 3 stages of labour?

1st stage- creation of birth canal

2nd stage- expulsion of the fetus

3rd- expulsion of placenta, contraction of uterus.


When can you first palpate the uterus?

At around 12 weeks.


What terms can be used to describe the position of the fetus during the end of pregnancy?





What does lie mean, with respect to the fetus in labour?

What's the most common?

it compares the relationship of the long axis of the fetus against the long axis of the mother.

Longitudinal lie is the most common.


What does presentation mean, with respect to the fetus in labour?

Which part of the fetus is adjacent to the pelvic inlet.

Most commonly the head, 'cephallic presentation'


What does vertex mean, with respect to the fetus in labour?

The orientation of the presenting part of the fetus,

Eg in cephallic presentation, you can have the minimum diameter, forehead, brow etc.


What is the diameter of presentation of the average fetal head?



What is the diameter of the typical pelvic inlet?



What can help to increase the diameter of the pelvic inlet during pregnancy?

Softening of the pelvic ligments, due to collaginases and prostaglandins.


What is 'Effacement'?

Bringing the external os of the cervix up to meet the internal os.

It is part of cervical ripening.


What is the cervix made up of structurally?

lots of collagen.

this needs to be broken down during labour to allow expulsion of the fetus.


What does ripening involve?

-reduction in the amount of collagen (done by collaginases)

-increase in glycoasaminoglycans

-increase in hyaluronic acid

-reducing aggregation of collagen fibres.


What is the purpose of glycsaminoglycans in cervical ripening?

They fit between the collagen strands, pulling them apart and increasing the surface area for the collaginases to work on

This leads to less rigidity of the cervix


What is the purpose of hyaluronic acid during cervical ripening?

It causes water to come in between the layers of tissue (like a blister)

Increases the area of collaginases etc to work on during cervical ripening.


Which muscle is responsible for generating force during partuition?

How does this happen?

The myometrium.

Raises in intracellular Ca2+, which occur due to spontaneous action potentials being formed by pacemaker cells.

The Calcium causes SM contraction.


What happens in early pregnancy, regarding contractions?

You get spontaneous contractions around every 30 minutes, but they are of low amplitude.


What's the name given to the contractions experienced in mid-pregnancy?

Braxton Hick's contractions.

They are of higher amplitude than the contractions experienced in early pregnancy, but occur less frequently.

They shouldnt result in expulsion of the fetus.


What happens to contractions during labour?

Early- variable timing but higher implitude.

Late- frequent contractions of even higher amplitude.


What defines clinical labour? (contractions)

Having contractions lasting at least a minute, 3 times within 10 minutes.


What is the action of prostaglandins on contractions?

Lead to increased intracellular calcium, so make contractions stronger.


What is the action of oxytocin on contractions?

They lower the treshold for action potentials, resulting in more action potentials and therefore a higher frequency of contractions.


What is the main factor involved in controlling prostaglandin and oxytocin levels/effects?

oestrogen:progesterone ratio.

If it is high, more prostaglandins are produced and released, and more oxytocin receptors are presented on the surface of the cells, so sensitivity for oxytocin is increased.

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