Preterm Labor

Question 1

Which is the first line tocolytic agent?

Answer 1

Nifedipine

(CCB)

Question 2

Definition of premature (preterm) labor

Answer 2

Onset of labour before 37 week’s gestation.

Question 3

Incidence of premature labour

Answer 3

1 in 8 of all deliveries

• accounts for 85% of all perinatal morbidity and mortality.

Question 4

Biggest three risk factors for preterm birth

Answer 4

1. intra-amniotic infection (50%)
2. multiple gestation (40%)
3. placental abruption (35%)

NB> Reliance on risk factors will fail to identify >50% of premature pregnancies.

Question 5

What vaginal infections have been associated with premature birth.

NB. routine screening and tx does not reduce risk

Answer 5

bacterial vaginosis

• Neisseria gonorrhoae
• Chlamydia trachomatis
• Trichomonas vaginalis

Question 6

Other than nifedipine (CCB), what other tocolytic agents can be used?

Answer 6

• progesterone supplementation; studies in progress, for high risk px.
• Atosiban (oxytocin receptor antagonist)
• B-Adrenergic agents; commonly used but higher maternal risks.

Question 7

What four mechanisms can cause premature labour?

Answer 7

• intrauterine infection/ inflammation
• maternal stress or fetal stress
• excessive uterine stretch (eg. multiple pregnancy)
• placental abruption

Question 8

causes of premterm birth - diagram

Answer 8

Question 9

Four mechanisms for preterm birth - diagram

Answer 9

Question 10

What is Fetal fibronectin and what is its role in preterm labor?

Answer 10

Fetal fibronectin (fFN) is a fibronectin protein produced by fetal cells. It is found at the interface of the chorion and the decidua (between the fetal sac and the uterine lining).

Fetal fibronectin “leaks” if a preterm delivery is likely. It’s value lies in its negative predictive value.

Question 11

What endocrine assay can be used to predict premature labor?

Answer 11

Elevated maternal salivary estriol in high risk patients.

Question 12

What is ‘intrauterine fetal demise’?

Answer 12

The death of a baby in the uterus.

The term is usually applied to losses at or after the 20th week of gestation

Question 13

Absolute contraindications for tocolytic agents?

Answer 13

• intrauterine infection
• fetal distress
• vaginal bleeding
• intrauterine fetal demise

Question 14

Are tocolytic agents effective?

Answer 14

Not really. Little evidence to support efficacy beyond 48 hours