Which is the first line tocolytic agent?
Definition of premature (preterm) labor
Onset of labour before 37 week's gestation.
Incidence of premature labour
1 in 8 of all deliveries
- accounts for 85% of all perinatal morbidity and mortality.
Biggest three risk factors for preterm birth
- intra-amniotic infection (50%)
- multiple gestation (40%)
- placental abruption (35%)
NB> Reliance on risk factors will fail to identify >50% of premature pregnancies.
What vaginal infections have been associated with premature birth.
NB. routine screening and tx does not reduce risk
- Neisseria gonorrhoae
- Chlamydia trachomatis
- Trichomonas vaginalis
Other than nifedipine (CCB), what other tocolytic agents can be used?
- progesterone supplementation; studies in progress, for high risk px.
- Atosiban (oxytocin receptor antagonist)
- B-Adrenergic agents; commonly used but higher maternal risks.
What four mechanisms can cause premature labour?
- intrauterine infection/ inflammation
- maternal stress or fetal stress
- excessive uterine stretch (eg. multiple pregnancy)
- placental abruption
causes of premterm birth - diagram
Four mechanisms for preterm birth - diagram
What is Fetal fibronectin and what is its role in preterm labor?
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.
What endocrine assay can be used to predict premature labor?
Elevated maternal salivary estriol in high risk patients.
What is 'intrauterine fetal demise'?
The death of a baby in the uterus.
The term is usually applied to losses at or after the 20th week of gestation
Absolute contraindications for tocolytic agents?
- intrauterine infection
- fetal distress
- vaginal bleeding
- intrauterine fetal demise
Are tocolytic agents effective?
Not really. Little evidence to support efficacy beyond 48 hours