Preterm birth

Question 1

Premature

Answer 1

Born before 37 weeks gestation

Question 2

Infection and PTB

Answer 2

Infection seen in 25-40% of all PTB
Pro-inflam response causes cervical remodelling and increased myometrial activity
IL1 - stim PG prod and myo contraction
TNFa- stim PG and MMP prod
IL8 - stim leuko influx associated with cervical ripening

Question 3

Defences against infection

Answer 3

Acid vaginal pH
Cervical mucus
Epithelial barrier
Innate immune response

Question 4

Ischaemia and PTB

Answer 4

Increased rate of vasc lesions in PTB and abruption
Isch - renin prod - AT2 release - increased myo contract and PG release
Thrombin - act common path of parturition. stim myo cont and MMP prod

Question 5

Cervical insufficiency

Answer 5

Prem cervical ripening

Question 6

Uterine overdistension

Answer 6

Multiples
Polyhydramnios
Uterine anomalies
Term equiv levels of stretch reached earlier therefor increased levels of contraction associated proteins

Question 7

Endocrine disorders

Answer 7

Progesterone promotes quies

Inflam pathways involved in PTB may cause functional prog withdrawal

Question 8

Predicting PTB

Answer 8

Current: history, cervical length, fetal fibronectin, infection screening, clinical diagnosis
Future: serum biomarkers, impedance spectroscopy, other cervical techniques

Question 9

Risk factors

Answer 9

Previous PTB, multiples, cervical surgery, uterine anomalies, smoking, race, age, BV, short cervix

Question 10

Fetal fibronectin

Answer 10

ECM pt at choriodecidual interface
Abnorm after 20wk may indicate abnorm attachment of membranes
normally increases as labour approaches

Question 11

FFN stats

Answer 11

Features of SPTB - 20% fFN +ve - 1/6 deliver in less than 14 days
10ng/ml - 99% chance of deliver AFTER 34 weeks

Question 12

Preventing PTB

Answer 12

Primary - popn risk
Secondary - select those at risk for surveillance
Tertiary - treatment after diagnosis to decrease morbidity

Question 13

Cervical cerclage

Answer 13

Placement of suture to prevent dilation of cervix
History-indicated - risk factor
US-indicated - Short cervical length but no membrane
Rescue - after dilation and present of mem
Suture left til late 3T or labour signs

Question 14

Prep for PTB

Answer 14

Antenatal corticosteriods - accel T1 and T2 pneumo & alv Na+ channels and increased surfactant pt trsc and trsl
Transfer to neonatal care unit
MgSO4

Question 15

Tocolysis

Answer 15

Delaying childbirth (by about 7 days)
Doesn’t improve neonat outcome but can be used to prep for early birth
Nifedipine (Ca channel blocker)
Atosiban (OTR antag)