Prevention and Management of Preterm Birth

Section 1: Introduction and Background

1.1 Definition of Preterm Birth

1.2 Burden in Malaysia

• Approximately 500,000 babies are born in Malaysia annually
• The preterm birth rate is approximately 12.3%
• Preterm birth is a leading cause of neonatal and infant mortality; risk of mortality increases as gestational age decreases
• It is aligned with the UN SDG Goal 3 (reduce neonatal mortality) and Malaysia's commitment to evidence-based maternity care

1.3 Classification by Aetiology

• Spontaneous preterm labour with intact membranes
• Preterm prelabour rupture of membranes (PPROM)
• Provider-initiated (iatrogenic) preterm birth - for maternal or fetal indications

1.4 Risk Factors

• Previous spontaneous preterm birth or second-trimester loss (16 to <37 weeks)
• Short cervix (cervical length ≤25 mm) detected on transvaginal ultrasound
• Previous cervical surgery or trauma (e.g., LLETZ > 10 mm depth)
• Multiple pregnancy
• Uterine anomalies
• Infections: urinary tract infection, genital infections
• Low pre-pregnancy BMI
• Smoking
• Extremes of maternal age

1.5 Role of Progesterone

Section 2: Screening Strategies

2.1 Who to Screen - Cervical Length

• Women with previous spontaneous preterm birth or second-trimester loss
• Women with a short cervix in a previous pregnancy
• Women with previous PPROM
• Previous cervical surgery/trauma (e.g., LLETZ >10 mm depth)
• Women with uterine anomalies

• All pregnant women (as part of the anomaly scan)

• Recommended timeframe: 16-24 weeks of gestation
• In high-risk populations, cervical length screening may be performed as early as the first-trimester anomaly scan

• Transvaginal ultrasound (TVU) measurement of cervical length is the recommended method
• Short cervix is defined as ≤25 mm

Section 3: Prevention

3.1 Progesterone

1. Previous spontaneous preterm birth or second-trimester loss (between 16 to <37 weeks of gestation)
2. Isolated short cervix (≤25 mm) between 16 and 24 weeks without a history of spontaneous PTB, PPROM, or cervical trauma

• Short cervix (≤25 mm) PLUS prior spontaneous preterm birth or second-trimester loss (16 to <37 weeks)

3.2 Cervical Cerclage

• Short cervix (≤25 mm) and PPROM in a previous pregnancy
• Short cervix (≤25 mm) related to previous cervical trauma
• Previous successful cerclage for cervical insufficiency in a prior pregnancy

3.3 Interventions with Limited or No Proven Benefit

• Bed rest
• Routine antibiotic prophylaxis (in the absence of infection)
• Home uterine monitoring
• Routine hydration/bed rest for threatened preterm labour without specific indications

Section 4: First Review and Follow-Up at O&G Specialist Clinic

• Full obstetric and cervical history
• Cervical length measurement by TVU
• Microbiological investigations where indicated
• Decision on prevention strategy (progesterone, cerclage, or combined)

• Flow Chart 1: Algorithm for Prevention of Spontaneous PTB - Initial and Further Risk Assessment at Peripheral Health Clinics
• Flow Chart 2: Algorithm for Prevention of Spontaneous PTB - Evaluation and Management at O&G Specialist Clinic

Section 5: Diagnosing and Treating Preterm Labour

5.1 Diagnosis of Preterm Labour

• Regular uterine contractions (at least 4 in 20 minutes or 8 in 60 minutes)
• Cervical changes (effacement and/or dilatation)
• Intact or ruptured membranes

5.2 Investigations

• FBC (Full Blood Count)
• MSU FEME and C&S (midstream urine, full and microscopic examination, culture and sensitivity)
• Cardiotocograph (CTG)
• Ultrasound assessment (Note: Exclude gross fetal anomaly)

5.3 Tocolysis

1. Completion of a course of antenatal corticosteroids
2. In-utero transfer to a facility with appropriate neonatal care

District hospital/peripheral clinic guidance: Administer SC terbutaline 0.25 mg stat for tocolysis to facilitate in-utero transfer.

• Non-reassuring fetal heart rate
• Clinical chorioamnionitis
• Placental abruption with fetal compromise

5.4 Antenatal Corticosteroids

• Neonatal death
• Respiratory distress syndrome (RDS)
• Intraventricular haemorrhage (IVH)
• Necrotising enterocolitis (NEC)
• Need for mechanical ventilation

• Dexamethasone OR Betamethasone 12 mg IM, two doses, 24 hours apart

• A rescue course may improve short-term outcomes (reduced RDS, less need for surfactant, reduced composite morbidity)
• However, there is concern about association with reduced birth weight, length, and head circumference - risks increase with more courses
• Repeat antenatal corticosteroids should be used with caution and factors to consider include: interval since last course, gestational age, and likelihood of delivery within 7 days
• There is no difference in long-term outcomes with rescue courses

5.5 Magnesium Sulphate for Fetal Neuroprotection

5.6 Intrapartum Antibiotics

• GBS (Group B Streptococcus) carriage in current pregnancy
• Preterm labour with unknown GBS status
• PPROM with known GBS carrier status
• Previous infant with invasive GBS disease
• GBS bacteriuria

• Preferred: Benzylpenicillin 5MU IV (initial dose), then 2.5-3MU IV q4h until delivery
• Alternative: Ampicillin 2g IV initial dose, then 1g IV q4h until delivery
• Mild penicillin allergy: Cefazolin 2g IV initial dose, then 1g q8h until delivery; OR Cefuroxime 1.5g IV stat then 750mg IV q8h
• Severe penicillin allergy: Vancomycin 15-20 mg/kg IV q8-12h OR Clindamycin 900mg IV q8h until delivery

• Non-GBS carrier: Erythromycin ethylsuccinate 400mg PO q6h (or 800mg PO q12h) for 7-10 days
• GBS carrier: Ampicillin 2g IV q6h for 48 hours PLUS Azithromycin 1g PO stat on admission, followed by Amoxicillin 500mg PO q8h for 5-7 days (or until delivery)

Summary of Key Recommendations at a Glance

Appendices Referenced in the Guideline

1. Appendix 1 - Preterm Birth Screening Checklist
2. Appendix 2 - Flow Chart 1: Algorithm for Prevention at Peripheral Health Clinics
3. Appendix 3 - Flow Chart 2: Algorithm for Prevention at O&G Specialist Clinic
4. Appendix 4 - Drafting Committee

Source: Malaysian MOH Guidelines on Prevention and Management of Preterm Birth (2023), MOH/P/PAK/516.23(GU)-e. Developed by the Obstetrical & Gynaecological and Paediatric Services Unit, Medical Development Division, MOH Malaysia, in collaboration with JPPOBG. Available at the MOH website.