L25 Childbirth

Question 1

What is considered preterm, viable and post dates

Answer 1

Preterm: <37 weeks
Viable: 23-24 weeks
Post dates: >41 weeks

Question 2

What are the signs of the onset of labour

Answer 2

Regular painful contractions, show: losing cervical mucus plug, rupture of membranes; water breaking and progressive cervical change

Question 3

What happens in the latent phase, how long does it take

Answer 3

It is the phase before active labour- duration variable 1-12 hours +. During this phase there is first effacement of the cervix then dilatation <3cm for nulliparous, otherwise both kind of together.
Some descent of head.

Question 4

What happens during the first stage of active labour phase

Answer 4

Regular painful contractions, cervical dilatation >3cm and fully effaced to full dilatation 10cm. Descent of the fetal head.

Question 5

What happens during the second stage of active labour phase

Answer 5

Full dilatation to birth of the baby- as the baby moves through the birth canal it goes through flexion, internal rotation of the head, extension as its head comes out, then restitution- external rotation of the head.
This stage is either active pushing, or passive descent with epidural.

Question 6

What happens during the third stage of active labour phase

Answer 6

From birth of the baby to expulsion of the placenta. The uterus contracts to shed the placenta and muscles clamp to occlude vessels.

Question 7

How is the third stage managed - and why

Answer 7

If low risk, there is no intervention and placenta is delivered by maternal effort- up to 60 min.
To reduce risk of post partum haemorrhage (loss <500mL).
1. Ecbolic - medication to contract the uterus eg syntocinon
2. Await signs of separation (uterine contraction, lengthening of cord, gush of blood)
3. Push uterus up with one hand to stop inversion, then controlled cord traction

Question 8

How and why is the fetus monitored during labour

Answer 8

If no risk factors: intermittent auscultation of fetal HS with doppler US to make sure they are fine after hypoxic period during contraction.
If risk: Continuous cardiotocograph if risk factors- see the fetal hr pattern compared to the uterine activity

Question 9

What are the 3 mechanical factors that determine progress through labour

Answer 9

Passenger: diameter of the babies head
Passage: dimension of the pelvis
Power: degree of force expelling the baby

Question 10

What are the 4 ways that the fetus’s position in relation to the mother is described - Passenger. Which position is preferred. What other factor plays a part in this

Answer 10

1. Fetal lie: usually longitudinal unless preterm. Cephalic- head down is preferred. Breech baby is feet first, transverse is most dangerous as cord could fall out
2. Position: relationship of the occiput (back of the head) (or sacrum if breech) to the maternal pelvic brim. Occiput anterior is best - back to the belly. Occiput posterior allow fetal head to deflex -not good
3. Engagement: how deep the presenting part is engaged in the bony pelvis- below or above the pelvic rim/pubic symphysis
4. Attitude: The degree of flexion of the fetal head: max flexion ideal because smallest diameter 9.5cm. Extension 90 degrees- presents brow 13-14 cm, but 120 degrees- presents face - technically deliverable by vagina
5. Fetal size (fundal height- symphysis pubis to top of uterus related to gestational age also plays a part

Question 11

How can the structure of the baby’s head help with birth

Answer 11

Fetal skull bones are not fused, separated by sutures and fontanelles which allows moulding of the head as it passes through the birth canal

Question 12

How does the bony pelvis influence birth movements and what measurement relates to this (passage)

Answer 12

Encourages the sequence of movements in stage 2
1. Inlet has a wider inlet transversely
2. The mid cavity is round and pelvic muscles guide baby to
3. Occiput anterior: as there is Wider AP diameter
Station measures the descent of the head on vaginal examination in reference to ischial spines ( descent below = + no.

Question 13

Where is the power generated for contraction in the uterus and what induces it

Answer 13

Oxytocin induces contractions 45-60 s every 2-3 minutes which are most powerful from the top as they push baby down and cervix open.

Question 14

Describe the 4 parts of delivery - exit out of the vagina

Answer 14

1. As the baby’s head reaches the perineum it extends to come out of the pelvis, crowns (+/- tear, episiotomy) and is born - pelvic floor pain.
2. Head restitutes rotating 90 degrees to adopt transverse position in which it entered the pelvis
3. Anterior shoulder comes under pubic symphysis
4. Rest of body follows

Question 15

What is considered slow progress for first stage of labour, what are possible causes and solutions

Answer 15

Slow is <2cm dilatation per 4 hours. Could be due to

1. Insufficient power - increase contraction strength and frequency with infusion of oxytocin
2. Malpresentation (occiput post) - allow more time and power for rotation; manual rotation and C section
3. Fetal size or Cephalo-pelvic disproportion - either passenger or passage- caesarean section

Question 16

What is considered slow progress for second stage of labour, what are possible causes and solutions

Answer 16

slow: active pushing >2hr (np) >1 hr (parous). If station +1 or more- midcavity or low consider instrumental delivery.
1. Forceps: Quicker, more control, safer for preterm, less neonatal birth injuries- but need to know presentation of baby (facial nerve palsy)
2. Ventouse: Rotation possible, make more swelling for traction, less force takes longer, more likely to fail

Question 17

What is considered slow progress for 3rd stage of labour

Answer 17

> 30 minutes but act earlier if haemorrhage