Women's Health : Preterm Labour

Question 1

Preterm Labour Definition

Answer 1

Onset of labour before 37 weeks gestation

Question 2

Aetiology of Preterm Labour

Answer 2

Similar mechanism to normal labour - probably due to: ○ Premature uterine stimulation ○ Premature withdrawal of pro-quiescent factors

Question 3

Causes of Prostaglandin Release

Answer 3

1. Intrauterine infection 2. Placental ischaemia / decidual haemorrhage 3. Uterine stretch 4. Foetal / maternal stress

Question 4

How can intrauterine infection trigger labor?

Answer 4

: Host inflammatory mediators respond to the infection, which can lead to the initiation of labor.

Question 5

How does uterine stretch contribute to labor initiation?

Answer 5

Uterine stretch (e.g., in multiple gestation or polyhydramnios) induces: Gap junction formation
Increased oxytocin receptors
Release of inflammatory cytokines and prostaglandins

Question 6

What role does uteroplacental ischemia play in labor initiation?

Answer 6

Uteroplacental ischemia (e.g., from spiral artery maladaptation, microthrombosis, or antepartum hemorrhage) activates thrombin, which leads to uterine contractions.

Question 7

How does fetal or maternal stress contribute to labor?

Answer 7

Stress activates the hypophyseal-pituitary-adrenal axis, increasing ACTH release, which can initiate labor.

Question 8

What is the significance of fetal fibronectin dissolution in labor?

Answer 8

Fetal fibronectin is an extracellular matrix protein that adheres the decidua to the chorion; its breakdown allows separation, facilitating labor.

Question 9

Who is offered Prophylactic treatment for Preterm Labour

Answer 9

Women with a history of previous preterm birth and cervical length <25mm are offered treatment

Question 10

What is the Prophylactic treatment for Preterm Labour

Answer 10

Vaginal progesterone or Cervical cerclage (suture)

Question 11

Methods of diagnosis and Investigations for Pre term labour which are the same as in term labour

Answer 11

History, abdominal and vaginal examination, observations, analgesia

Question 12

Additonal methods of Dx and Ix for Preterm labour?

Answer 12

Speculum examination to assess for P-PROM ○ Transvaginal ultrasound to measure cervical length or foetal fibronectin testing

Question 13

First Line Managment for Preterm Labour?

Answer 13

maternal corticosteroids (to aid foetal lung maturation): ○ Indicated if labour before 34 weeks ○ Offer betamethasone or dexamethasone, 2 doses 12 hours apart.

Question 14

Additional Managment for Preterm Labour?

Answer 14

Plus: magnesium sulphate (neuroprotection - reduces incidence of intraventricular haemorrhage) ○ Indicated if labour before 30 weeks (can be given up to 34 weeks) ● Plus: tocolysis (suppression of contractions) ○ Offer nifedipine before 34 weeks gestation. ● Plus: term labour management and monitoring.

Question 15

What additional treatment is given for neuroprotection?

Answer 15

Magnesium sulphate

Question 16

When is magnesium sulphate indicated?

Answer 16

Labour before 30 weeks (can be given up to 34 weeks)

Question 17

What is tocolysis?

Answer 17

Suppression of contractions

Question 18

What is offered for tocolysis?

Answer 18

Nifedipine before 34 weeks of gestation

Question 19

What is PROM at term?

Answer 19

Prelabour Rupture of membranes before labour after 37 weeks

Question 20

Define PROM

Answer 20

Spontaneous rupture of membranes before the onset of labour at term (after 37 weeks gestation).

Question 21

What percentage of women with PROM go into labour within 24 hours?

Answer 21

0.6

Question 22

Ix for PROM

Answer 22

Speculum examination - only if doubt as to whether membranes have ruptured. Otherwise a clinical diagnosis based on history

Question 23

What warrants immediate induction for PROM?

Answer 23

History of group B strep infection

Question 24

Management for PROM

Answer 24

Expectant management up to 24 hours (with 4-hourly self-monitoring of temperature) or: ● Induction of labour; also offered if labour does not start with expectant management. ● Note: previous history of group B streptococcus infection warrants immediate induction for PROM, with intrapartum antibiotics (benzylpenicillin)

Question 25

P-PROM

Answer 25

Preterm Prelabour Rupture of Membranes

Question 26

Define P-PROM

Answer 26

Rupture of membranes before 37 weeks without spontaneous labour

Question 27

What is the first line diagnostic method for P-PROM?

Answer 27

Speculum examination

Question 28

What does a speculum examination show in P-PROM?

Answer 28

Pooling of amniotic fluid

Question 29

What tests may be offered if no pooling is seen for P-PROM?

Answer 29

offer second line: insulin-like growth factor binding protein-1 test or placental alpha microglobulin-1 test

Question 30

First Line Management for P-PROM

Answer 30

prophylactic antibiotics ; PO erythromycin for 10 days / until established labour