22. Pregnancy and birth

Question 1

Initiation of birth

Answer 1

Remains uncertain
Multifactorial in origin
		•hormonal
		•mechanical
Fetal hypothalamus is triggered
Maternal post pituitary releases oxytocin
Decidua releases prostaglandins

Question 2

Physiology of the initiation of labour

Answer 2

↑ in oestrogen pro-labour hormone
↓ in progesterone pro-pregnancy hormone
Release of oxytocin by the mother’s posterior pituitary gland
Prostaglandins from the decidua
Together creating uterine contractions
Mechanical stimulation of the uterus and cervix caused by overstretching and pressure from the pp

Question 3

Diagnosis of labour

Answer 3

Not always water breaking
Regular uterine contractions
Take average 10 minutes and get women to count how many - aim for 3 or 4 regular contractions in 10 minutes

Question 4

Stages of labour

Answer 4

Latent phase

1st stage of labour

2nd stage of labour

3rd Stage of labour.

Question 5

Latent phase of labour

Answer 5

Effacement of cervix
Contractions
Intensity varies

Question 6

Effacement of the cervix

Answer 6

Effacement is the gradual thinning, shortening and drawing up of the cervix measured in percentages from 0 to 100%

Like a turtle neck jumper being pulled over a head - cervix gets effaced then dilated. When haven’t had a baby before this can take a few days (whereas if have had a baby, then have muscle memory) and is very tiring.

Question 7

Diagnosis of active labour

Answer 7

Painful regular contractions
Cervical effacement
Dilatation of the cervix of 4cms or more.

Question 8

Active labour/first stage of labour

Answer 8

Established labour to full cervical dilatation
Vaginal examinations
Average is 0.5cm/hour

Question 9

Descent of the foetal head in relation to the ischial spines

Answer 9

Progress measured by dilatation and descent of the fetal head (in relation to the pelvic brim and the ischial spines)

Question 10

Second stage of labour

Answer 10

From full dilatation to the delivery of the baby

Women will feel like they have to push the baby out, it will get more intense

Question 11

Pelvic inlet

Answer 11

The brim is oval except where the promontory projects
The anteroposterior diameter is 12cm
baby sticks head through pelvic inlet sideways for more room

Question 12

Pelvic outlet

Answer 12

The outlet is diamond shaped
Its three diameters are:
 - anteroposterior (as the coccyx is deflected backwards this is the space available during birth)
 - oblique
 - transverse

Question 13

Fontanelles

Answer 13

Anterior fontanelle (bregma)
•	diamond shaped intersection of 4 
•  sutures
•	2x3 cms
•	closes at 18 months

Posterior fontanelle
• Y shaped intersection of 3 sutures
• closes at 6-8 weeks

Question 14

Diameters of the fetal skull

Answer 14

Suboccipitobregmatic (9.5cms) = OA position

Occitopitofrontal ( 11cms) = OP position

Supraoccipitomental ( 13.5 cms) = brow

Submentalbregmatic (9.5cms) = face

Question 15

Mechanism of birth

Answer 15

Head at pelvic brim OccipitalTransverse (OT) position
Flexion of neck (Suboccipitobregmatic)
Head descends and engages
Head reaches pelvic floor- rotates to Occipital Anterior
Head delivers by extension
Head “restitutes” (comes in line with the shoulders)
Shoulders rotate into anterior/posterior diameter of pelvis
Anterior shoulder delivered by lateral flexion from downward pressure on baby’s head
Posterior shoulder by upward lateral flexion

Question 16

Third stage of labour

Answer 16

Delivery of placenta

Normal Estimated Blood loss 300-500mls

Inspection of placenta to ensure completion

Question 17

Management of third stage of labour

Answer 17

Either:

1.Active management (CCT)
Oxytocin i.m. given into maternal thigh
Cause sustained uterine contraction
Aids delivery of the placenta & contraction of the placental bed
Decreases risk of Post Partum Haemorrhage (PPH)

Or

2.Physiologigal: Mother naturally expels the placenta and membranes with contractions.

Question 18

Foetal monitoring in labour

Answer 18

Why?
to detect fetal hypoxia and deliver baby if needed
How?
Screening the fetal heart rate by
Intermittent auscultation by Pinard or Sonicaid
CTG (cardiotocograph)
FBS

Question 19

Intermittent auscultation

Answer 19

Every 15 mins before and after a contraction during the first stage
Every 5 minutes in the second stage
Any abnormality heard would lead to the use of the CTG

Question 20

Cardiotograph

Answer 20

Continuous print out of fetal heart rate and contractions
Abdominal ultrasound
detects cardiac movements and hence heart rate
A clip applied to the fetal scalp (FSE)
detects the R-R wave of the fetal ECG
Most usual is the abdominal ultrasound

Question 21

Foetal blood sample

Answer 21

Why?
CTG is highly sensitive e.g. if normal, baby OK
But poorly specific e.g. if abnormal only a few babies are hypoxic
Use of CTG leads to a 4 fold increase in Caesareans Sections for fetal distress
therefore
Need to check the CTG findings with FBS

Question 22

FBS procedure

Answer 22

Stab on the fetal scalp
Blood collected via a glass pipette
pH and base excess result
Contraindications:
Infection such as HIV, Hepatitis B 
Fetal Bleeding disorder
Prematurity less than 32 weeks