Preterm labor Important cause of perinatal mortality &
morbidity 50 % of all major neurologic handicaps
Slide 3
Increased in survival Use of C.S Regionalization prenatal care
Improved method of mechanical ventilation Use of surfactant
Improved nutritional therapy
Slide 4
Mechanism of labor onset Hormonal (progestron withdrawal)
Oxytocin Prostaglandins Cytokines IL.1-IL.6-TNF ( stimulate the
amnion and decidua to produce PG) B-TGF ( inhibit PG production)
Other factors endothelin nitric oxide (NOS)
Slide 5
Infection as a cause of preterm labor Linked with symtomatic
nongenital infection Subclinical Infection an important cause of
PTL a- Histologic chorioamnionitis increased b- recognized
infections in mother and neonates c- sepsis and meningitis are
increased 3 to 10 fold d- positive culture of amniotic
fluid/membrane/decidua 3-24% (
Fetal fibronectin presence 20-34 w strongly associated with PTL
Sensitivity is low Specificity is high Used to women with intact
membrane, cervical dilation less than 3 cm,GA 24-34 w results
should be available within 24h False positive (recent
intercourse-vaginal examination presence of B.V -vaginal bleeding)
>50 ng positive test
Slide 20
All of these tests fail to meet the goals of an ideal screening
test
Slide 21
Preterm labor defined uterin contractions >4 contractions
per 20 minutes Cervical dilation 2cm or more in N..P 3cm or more in
M.P Cervical effacement > 80% Uterin contraction and cervical
change
Absolute CI of tocolytic theraphy Severe preeclampsia Severe
abruptio Severe bleeding Frank chorioamnionitis Fetal death Fetal
anomaly incompatible with live Severe FGR Mature lung Maternal
cardiac arrythmia
Slide 24
Relative CI to tocolytic therapy Mild chronic hypertension Mild
abruptio Stable previa Maternal cardiac disease Hyper thyroidism
Uncontrolled diabetes Fetal distress Fetal anomaly Mild IUGR Cervix
dilatation greater than 4 cm
Slide 25
B - adrenergic agonists The most wildly prescribed Ritodrined
and terbutaline (SC-IV) Disadvantage - side effect(none of them are
completely B2 selective ( Negative B2 effect Maternal hypotension
Decreased u.o.p increased glucose secretion Hypokalemia Pulmonary
edema
Severe maternal adverse effect Cardiac arrhythmia Myocardial
infraction Pulmonary edema Postpartum cardiomyopathy death
Slide 28
Fetal effect Tachycardia Increased C.O.P Redistribution of
blood flow Increased thickness of inter ventricular septum Neonatal
supra ventricular tachycardia Myocardial ischemia and necrosis
hydrops Hypoglycemia Intra ventricular hemorrhage
Slide 29
Are B-mimetics efficacious?
Slide 30
Magnesium sulfate In recent years, tocolytic of choice in many
delivery units Protocol of administration The blood levels of
6-8mg/dl are optimal for tocolysis
Slide 31
Maternal side effect Common (flushing-sense of warmth-headache
nystagmus-nausea-dizziness-lethargy) Serious (pulmonary
edema-neuromuscular blockage- osteopenia-respiratory
depression-cardiac arrest)
Slide 32
Neonatal side effect Respiratory depession Decreased beat to
beat variability Decreased muscle tone Drowsiness Depression Poor
respiratory effort Low apgar score
Slide 33
Is mgso4 ?efficacious
Slide 34
Ca channel blocker Mechanism Protocol of Ad Maternal side
effect Decrease in mean arterial pressure Symptomatic hypotension
Nausea-headache-facial flushing
Slide 35
Neonatal side effect Well tolerated by the fetus Neonatal heart
block Growth restriction, acidosis, stillbirth No protocol
established the safety of using these medication together
Slide 36
Prostaglandin synthesis inhibitors Mechanism Protocol of Ad
Fetal CI Growth restriction Renal anomaly Oligohydramnios
Chorioamnionitis Ductal dependant cardiac lesion Twin to twin
transfusion syndrom
Slide 37
Maternal CI Renal and hepatic D Active peptic ulcer Poorly
control H.T Asthma in aspirin-sensitive patients Coagulation
disorder Maternal side effect GI upset and hemorrhage Alteration in
coagulation Thrombocytopenia Asthma in aspirin-sensitive patients
Renal injury(prolonged treatment)
Slide 38
Neonatal side effect Constriction of ductus arteriosus Neonatal
PHT 5-10% Oligohydraminous increased ADH direct effect on renal
blood flow Necrotizing enterocolitis Intraventricular
hemorrhage
Slide 39
Effective agent that is well tolerated by mother and fetus
Indomethacin to be comparable to ritodrine and MgSo4 Exposure
should be limited to 48 hrs and G.A less than 32 weeks
Maintenance tocolysis following arrest of PTL Oral tocolysis
with B-mimetic Continous subcutaneous administration of terbutalin
Oral MgSO4 Oral nifedipine Long-term tocolysis with prostaglandin
synthetases inhibitors is contraindicated
Slide 42
Maintenance tocolytic agent .
Slide 43
Ancillary therapy for women in PTL Antibiotic therapy
Antibiotic therapy in PTL with intact membrane is not indicated GBS
prophylaxis should be administered Hydration therapy Bed rest C.S
(all women at risk for PTL prior to 34 weeks receive C.S
Slide 44
Key points 1. The rate of PTL is increasing in the united
states. 2. fFN and vaginal ultrasound of cervix and promising
technologies to identify women at risk for preterm delivery. 3.
Screening for B.V and T.Vaginal is not indicated. 4. Management of
women with asymptomatic shortening of the cervix controversial 5.
Tocolytic therapy has not been associated with improvements in
neonatal outcome. 6. Weekly courses of antenatal C.S should not be
routinely prescribed. 7. Antenatal progesteron therapy may reduce
the risk of preterm birth (PTB) and low birth weight (LBW) in women
with previous PTB