Summary Preterm Labour

Preterm Labour
Preterm labour = Onset of labour before 37-0/7 weeks’ gestaton

Epidemiology
 8-12% (1 in 8) of all deliveries
 Accounts for 85% of all perinatal morbidity and mortality

Risk factors (and relatve risk)
 Intra-amniotc infecton (x50)
 Multple gestaton (x40)
 3rd trimester vaginal bleeding (x10), e.g. placental abrupton (x35)
 Uterine anomalies (x5-7)
 Prior preterm delivery (x2-5)
 DES exposure (x4)
 Maternal age >35 (x2-3)
 UTI (x2)
 Smoking >10/day (x2)
 Illicit drug use, especially cocaine (x2)
 Black ethnicity (x2)
 Low socioeconomic status (x2)

Aetology
 Spontaneous (80%)
- Intra-amnioti infeiton – 30%
- Preterm premature rupture of membrane (PPROM) – 20-25%
- Idiopathii – 20-25%
- Plaiental abrupton – 5%
- Cerviial insufiieniy - <1%
 Non-spontaneous (20%)
- Iatrogenii/intentonal (e.g. due to IUGR, preeclampsia)

Pathophysiology
1) Major mechanisms:
- Inflammaton of uterus (e.g. UTI, intra-amniotc infecton)  breakdown of foetal membranes (by
bacterial enzymes, infammatory cells etc.)
- Exiessive uterine stretih (e.g. twins, polyhydramnios)  early actvaton of Ferguson refex
- Deiidual haemorrhage (e.g. placental abrupton)  uterine contractons to prevent bleed
- Maternal stress (e.g. depression) or Foetal stress (e.g. IUGR)  Actvaton of HPA axis
2) This leads to
- A breakdown in the mechanisms responsible for maintaining uterine quiescence throughout
pregnancy OR
- A short circuitng or overwhelming of the normal parturiton cascade
3) Labour is prematurely triggered

Complicatons
 Prematurity is the BIGGEST cause of Neonatal death (i.e. death in frst 28 days of life)
 Neurodevelopmental defiit (Cerebral palsy, learning difcultes, visual impairment)

Diagnosis/Screening
 Examinaton
- Abdo exam - Uterine iontraitons –more intense and frequent than Braxton hicks