Preterm Labor
早产
林建华
epidemiology
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Labor and delivery between 28 – 36+6 weeks
5%-10%
be the leading cause of perinatal morbidity
and mortality
Survival rates have increased and morbidity
has decreased because of technologic
advances
Risk Factors
Previous preterm delivery
• Low socioeconomic status
• • Maternal age <18 years or >40 years
• Preterm premature rupture of the membranes
• Multiple gestation
• Maternal history of one or more spontaneous
second-trimester abortions
• Maternal complications (medical or obstetric)
--Lack of prenatal care
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• Uterine causes
Myomata (particularly submucosal or
subplacental)
Uterine septum
Bicornuate uterus
Cervical incompetence
• Abnormal placentation
• Infectious causes
Chorioamnionitis
Bacterial vaginosis
Asymptomatic bacteriuria
Acute pyelonephritis
Cervical/vaginal colonization
• Fetal causes
Intrauterine fetal death
Intrauterine growth retardation
Congenital anomalies
diagnosis
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cervical effacement and/or dilatation
increased uterine irritability before 37 weeks
of gestation
forecast:
 uterine activity monitoring.
 Ultrasound Examination of Cervical length
 Fetal Fibronectin
treatment
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Bed Rest
Tocolysis
Corticosteroid Therapy
Antibiotic Therapy
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Although bed rest is often prescribed for
women at high risk for preterm labor and
delivery, there are no conclusive studies
documenting its benefit.
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A recent meta-analysis found no benefit to
bed rest in the prevention of preterm labor or
delivery.
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Tocolytic therapy may offer some short-term
benefit in the management of preterm labor.
A delay in delivery can be used to administer
corticosteroids to enhance pulmonary
maturity and reduce the severity of fetal
respiratory distress syndrome,
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also be used to facilitate transfer of the
patient to a tertiary care center
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No study has convincingly demonstrated an
improvement in survival, long-term perinatal
morbidity or mortality, or neonatal outcome
with the use of tocolytic therapy alone.
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Tocolytic Therapy
Magnesium sulfate (Intracellular calcium
antagonism)
Terbutaline (Bricanyl) Beta2-adrenergic
receptor agonist sympathomimetic;
decreases free intracellular calcium ions
Ritodrine (Yutopar) Same as terbutaline
Nifedipine (Procardia) Calcium channel
blocker
Indomethacin (Indocin) Prostaglandin
inhibitor
Potential Complications Associated With the
Use of Tocolytic Agents :
Magnesium sulfate
• Pulmonary edema
• Profound hypotension*
• Profound muscular paralysis*
• Maternal tetany*
• Cardiac arrest*
• Respiratory depression*
Beta-adrenergic agents
• Hypokalemia
• Hyperglycemia
• Hypotension
• Pulmonary edema
• Arrhythmias
• Cardiac insufficiency
• Myocardial ischemia
• Maternal death
Indomethacin (Indocin)
• Renal failure
• Hepatitis
• Gastrointestinal bleeding
Nifedipine (Procardia)
• Transient hypotension
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Corticosteroid Therapy
Dexamethasone and betamethasone
for fetal maturation reduces mortality,
respiratory distress syndrome and
intraventricular hemorrhage in infants
between 28 and 35 weeks of gestation.
benefits start at 24 hours and last up to
seven days after treatment
The potential benefits or risks of repeated
administration of corticosteroids after seven
days are unknown.
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women who received antibiotics sustained
pregnancy twice as long as those who did not
receive antibiotics
had a lower incidence of clinical amnionitis.
poor fetal outcome (death, respiratory distress,
sepsis, intraventricular hemorrhage or
necrotizing colitis) occurred less frequently in
women receiving antibiotics