Preterm Labour Flashcards
What is the definition of preterm birth (PTB)?
Birth before 37 completed weeks of gestation
PTB is a major obstetric problem, with an incidence of 8.6% of annual births.
What is the incidence of preterm birth (PTB) globally?
8.6% of the annual births
The incidence of PTB is increasing throughout the world.
What are the categories of preterm birth based on gestation?
- Extreme prematurity: <28 weeks
- Severe prematurity: 28-31+6 weeks
- Premature: 32-33+6 weeks
- Near term: 34-36+6 weeks
Near term accounts for 60% of premature deliveries.
List some maternal risk factors associated with preterm birth.
- Lower socioeconomic status
- Smoking
- Low pre-pregnancy weight <55kg
- Maternal age <18 years and >40
- Poor nutrition
These factors increase the risk of preterm labor.
What obstetric history risk factors are associated with preterm birth?
- Shortened cervix
- Cervical surgery (e.g., cone biopsy)
- Previous history of repeat TOP
- Previous second trimester miscarriage
These factors contribute to the likelihood of PTB.
What pregnancy complications are risk factors for preterm birth?
- Multiple pregnancy
- Infections
- Bleeding <24 weeks
- Previous preterm delivery (risk: 17 to 37%)
These complications can trigger premature labor.
What are some risks of prematurity for the baby?
- Neonatal death
- Respiratory distress syndrome (RDS)
- Necrotising enterocolitis (NEC)
- Intraventricular haemorrhage (IVH)
- Infection
- Jaundice
- Hypothermia
- Hypoglycaemia
- Long-term: developmental delay, cerebral palsy, blindness, deafness, poor educational attainment, broncho-pulmonary dysplasia
These complications can have severe long-term effects on a child’s health.
What is the aetiology of preterm labor?
- Cervical weakness
- Infection
- Decidual haemorrhage and placental abruption
- Uterine distension from multiple pregnancy
- Maternal illness
- Fetal stress
These factors contribute to initiating preterm labor.
What is the significance of cervical length in assessing preterm birth risk?
A cervical length less than 15 mm is a sensitive predictor of severe prematurity, associated with a 50% risk of delivery prior to 32 weeks’ gestation
Cervical length is measured via transvaginal ultrasound.
What does funnelling of the cervix indicate?
Opening of the internal os with a closed cervix below; an independent risk factor for PTL
Cerclage is not recommended for funnelling in the absence of cervical shortening.
What is fetal fibronectin?
An extracellular matrix glycoprotein found in cervico-vaginal secretions prior to labor
Detection after 24 weeks indicates an increased risk of delivery within 7 days.
What are some preventative strategies for preterm labor?
- Educational programs
- Home uterine activity monitoring
- Cervical suture insertion
- Screening and treating bacterial vaginosis (BV)
Treating BV has shown a documented reduction in preterm birth rates.
What is the role of progesterone in preventing preterm labor?
Acts as an anti-inflammatory agent, reducing the risk of PTL in women with a singleton pregnancy and a previous history of preterm delivery
Evidence on improving neonatal outcomes is limited.
What are the main tocolytics used for managing preterm labor?
- Calcium channel blockers (e.g., nifedipine)
- Oxytocin antagonists (e.g., atosiban)
Ritodrine is no longer recommended due to adverse maternal side effects.
What are the contraindications for tocolysis?
- Severe hemorrhage
- Abruption
- Severe preeclampsia
- Eclampsia
- Intrauterine fetal death
- Severe intrauterine growth restriction
- Fetal maturity
- Chorioamnionitis
These conditions indicate that tocolysis should not be attempted.