Module 5: Preterm, PROM and multiple pregnancy Flashcards
What is preterm birth
Labour that occurs after 20 weeks’ gestation and before 37 weeks’ gestation
Incidence of preterm birth in Australia
In most developed nations 5-10% and has increased to 8.5% in Australia.
Rates of morbidity with preterm birth
75-85%, 2/3 of perinatal deaths
How does infection affect preterm labour
Inflammatory cytokines or bacterial endotoxins can stimulate prostaglandin release directly or indirectly by stimulating the release of cortiocotrophin-releasing hormone.
Infection may be predictive of preterm birth at least 40% of the time
Risk factors for preterm birth
- Demographic: Higher incidence among low socioeconomic, poor education and poverty
- Past obstetric history. Risk after one 15%, two 41%
- Women >34 years
- Medical conditions: diabetes, hypertension, heart disease
- Current pregnancy: pre-eclampsia, major birth defects, placental abruption
- Behavioral: stress, psychological issues
- Environmental
Known causes of preterm birth
- Multiple pregnancy
- Short pregnancy interval
- Polyhydramnios
- Infections
- Births following ART and ovulation induction.
- Incompetent’ weak cervix
- Premature separation of placenta
- Excessive use of alcohol, smoking and narcotics
- APH
- 40-50% have no obvious cause
Cervical assessment
Used when women have a history of preterm birth, second trimester miscarriages, current risk of preterm birth, twins and those who have had cervical surgery
Ultrasound surveillance of the length of the cervix to check for shortening and dilatation
Assessment by experienced sonographers to determine in a cerclage is warranted.
Intervention may be required in cervix is <25 mm.
Fetal fibronectin testing
fFN is a glycoprotein localised at the maternal-fetal interface of the amniotic membranes. In normal conditions fFN is found in very low levels. Levels >50ng/ml at or after 22 weeks have been associated with an increased risk of preterm birth. fFN is one of the best predictors so far.
Fetal fibronectin testing indications
- Singleton pregnancy
- 24-34 weeks gestation
- TPL - regular uterine contractions >6 per hour and/or pelvic pressure.
- High risk of preterm delivery
- Intact membranes
- Cervix <3cm dilatation and no cerclage
- Established fetal wellbeing
Negative fetal fibronectin meaning
Woman is unlikely to deliver within the next 7-10 days with a 95% probability
Avoid unnecessary hospitalization, testing and reduces interventions/costs.
Tocolytic therapy
The attempt to stop or limit uterine contractions in preterm labour
Tocolytic drugs
Betamimetics eg IV salbutamol, terbutaline and ritodrine relax smooth muscle cells. Causes rapid pulse, chest pain, headaches. Contraindicated in cardiac disease
Calcium channel blockers e.g. oral nifedipine reduce muscle contraction by controlling the influx of calcium across the plasma membrane.
MgSO4 indications
- Preterm fetus <30 weeks
- Preterm birth expected in <24 hours, treatment to commence as close as 4 hours before
- 4g loading dose and titrated
- Used for singleton or twin pregnancies
MgS04 use
For neuroprotection of the preterm infant to minimise the risk of cerebral palsy
S/S of premature labour
Cervix begins to efface and dilate
Contractions that occur every 6-10 minutes that lasts for 30 seconds for at least an hour.
