Preterm labor

Question 1

What is the definition of preterm labor?

Answer 1

Onset of labor between 20 - 36+6 weeks.

Question 2

What are the RF for preterm labor?

Answer 2

CERVIX

• previous induced abortion
• previous cx trauma (diathermy, LLETZ, cone bx)
• short cervix <15mm
• infections

BABY

• abnormalities
• polyhydramnios
• multiple pregnancy

MOTHER

• smoking
• etoh
• cocaine

OTHER

• previous premature birth
• PPROM

Question 3

What are the clinical features of premature birth?

Answer 3

• presence of RF
• menstruation-like cramping
• mild, irregular contractions
• low back ache
• pressure on vagina
• blood/discharge

PPROM = high likelihood

Cervical exam:
- dilation.

Question 4

What is the order of investigations if a woman presents with those CF?

Answer 4

History - screen for RF
Rhesus status??
Vitals - ensure mother is hemodynamically stable.

Exam:

1. Uterus
   - tone
   - boggy
   - fundal height
   - pain/tenderness
   - fetal position
2. CTG
   - Fetal wellbeing
   - Contractions - strength, frequency.
3. Cervical exam: speculum only, not VE
   - dilation (<15mm unlikely prem labor)
   - effacement
   - blood loss quantity
   - membrane integrity (PPROM - likely lead to premature labor)
   - presenting part
4. Bedside investigations:
   - vaginal swab: infection (GBS, STIs)
   - fetal fibronectin (fFN) - predictive negative value.
5. Imaging
   Cervical TVUS - cervical length (<15mm unlikely PL)

Question 5

What are the primary, secondary and tertiary managements of premature labor?

Answer 5

Primary = public health and education

• avoid pregnancy at extremes of age
• no studies done.

Secondary = identifying risk factors in pregnant women to prevent PL

• promote general good health: no smoking, bedrest.
• infection screening
• vaccinations
• good antenatal care - identifying RF

If at risk:

• cervical cerclage
• progesterone (decreases uterine tone, antiinflammatory, good outcomes)

Tertiary = Acute management.
1. <32 weeks: Indomethicin (NSAID) + Nefidipine. Calcium channel blocker - stops uterine contractions. Stops labor for 2-7 days. Enables corticosteroid administration + transfer to tertiary centre
>32 weeks - Nefidipine ONLY.

2. Corticosteroid administered 20-34 weeks: lung maturation of the fetus, decreases respiratory distress syndrome of the new born.
3. MgSO4 - If birth is imminent @ 24 - 30weeks.
   = neuroprotection.
4. Immediate transfer to tertiary centre.

Question 6

What is PPROM, what are the RF, how does it present and how is it managed?

Answer 6

D- preterm premature rupture of membranes. Rupture of membranes between 20-37+6.

E - 50-10%

RF

• vaginal infection
• multiple gestation
• polyhydramnios

Complications

• 50-75% - premature labor
• chorioamnionitis
• sepsis mother and child
• child: skeletal deformities + lung hypoplasia (amniotic fluid no longer bathes lungs - high rate <24 weeks)

Dx

• water breaks early.
• sterile speculum to r/o prolapse.

Mx
- avoid swab/VE - decrease infection risk.

PL: as above
No PL:
- antibiotics
- corticosteroids (high risk of PL)
- Vitals + CTG regularly
- FBC: WCC + CRP (WCC rises after steroid administered therefore CRP better predictor)
- bed rest. 
- can be managed as outpatient. 

Delivery 34-35weeks.

Higher threshold of suspicion if proven vaginal/urinary infection.

Question 7

What is the MOA of Nifedipine?

Answer 7

Ca channel blocker - inhibits calcium mediated uterine contractions.

SE - severe headache, peripheral edema, fatigue.

Question 8

What are the complications of preterm labor on the baby?

Answer 8

• retrolental fibroplasia (retinopathy of premature labor: due to excess O2)
• respiratory distress syndrome
• intraventricular hemorrhage (IVH)
• bronchopulmonary dysplasia (BPD)
• necrotising entercolitis
• anemia
• jaundice