Pregnancy and birth

Question 1

Initiation of labour

Answer 1

Remains uncertain

Multifactorial in origin

• hormonal
• mechanical

Fetal hypothalamus is triggered

Maternal post pituitary releases oxytocin

Decidua releases prostaglandins

Question 2

Hormones in the initiation of labour

Answer 2

Increase in pro-labour hormone

Decrease 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

Stages of labour

Answer 3

Latent phase

1st stage of labour

2nd stage of labour

3rd stage of labour

Question 4

Latent phase of labour

Answer 4

Effacement of cervix

Contractions

Intensity varies

Question 5

Diagnosis of active labour

Answer 5

Painful regular contractions

Cervical effacement

Dilation of the cervix of 4cms or more

Question 6

Active labour/ first stage of labour

Answer 6

Established labour to full cervical dilation

Vaginal examinations

Average is 0.5cm/ hour

Question 7

Second stage of labuor

Answer 7

From full dilation to the delivery of the baby

Question 8

Pelvic inlet

Answer 8

The brim is oval except where the promontory projects

The anteroposterior diameter is 12cm

Question 9

Pelvic outlet

Answer 9

The outlet is diamond shaped

Has three diameters

• anteroposterior
• oblique
• transverse

Question 10

Fontanelles

Answer 10

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 11

Diameters of the fetal skull

Answer 11

Suboccipitobregmatic (9.5cms)- OA position

Occipitofrontal (11cms)- OP position

Supraoccipitomental (13.5cms)- brow

Submentalbrgmatic (9.5cms)- face

Question 12

Mechanisms of birth (9)

Answer 12

1. Head at pelvic brim OT position
2. Flexion of neck
3. Head descends and engages
4. Head reaches pelvic floor- rotates to OA
5. Head delivers by extension
6. Head restitutes
7. Shoulders rotate into anterior/ posterior diameter of pelvis
8. Anterior shoulder delivered by lateral flexion from downward pressure on baby’s head
9. Posterior shoulder by upward lateral flexion

Question 13

Third stage of labour

Answer 13

Delivery of placenta

Normal estimated blood loss 300-500 mls

Inspection of placenta to ensure completion

Question 14

2 types of third stages of labour

Answer 14

Active management

Physiological

Question 15

Active management of third stage

Answer 15

Oxytocin i.m. given into maternal thigh

Cause sustained uterine contraction

Aids delivery of the placenta and contraction of the placental bed

Decreases risk of post-partum haemoorhage

Question 16

Physiological third stage

Answer 16

Mother naturally expels the placenta membrane with contractions

Question 17

Fetal monitoring in labour

Answer 17

To detect fetal hypoxia and deliver baby is needed

Intermittent auscultation by Pinard or Sonicad

CTG

FBS

Question 18

Intermittent auscultation

Answer 18

Every 15 mins before and after a contraction during the first stage

Every 5 mins in the second stage

Any abnormality heard would lead to the use of the CTG

Question 19

Cardiotograph

Answer 19

Continuous print out of fetal heart rate and contraction

• abdominal ultrasound (detects cardiac movements)
• a clip applied to the fetal scalp (detects R-R wave of fetal ECG)

Most usual is abdominal ultrasound

Question 20

Fetal blood sampling

Answer 20

CTG is highly sensitive but poorly specific

Use of CTG leads to 4 fold increase in C-sections for fetal distress

Need to check the CTG findings with FBS

Question 21

FBS

Answer 21

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