Transcript Preterm Labor

Preterm Labor
Williams CH.36
Preterm Birth

Death, severe neonatal morbidities
Common before 26 weeks
 Universal before 24 weeks
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Worse Outcomes
Chronic lung disease
 Grade 3 and 4 intraventricular
hemorrhage
 Periventricular leukomalacia
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Threshold for neonatal mortality: 1600g
 Threshold for neonatal morbidity: 1900g

Cause of Preterm Birth
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Medical and obstetrical complications
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Preeclampsia, fetal distress, IUGR, placenta
abruption
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History of threatened abortion
 Lifestyle factors
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Smoking, inadequate weight gain, drug abuse, age,
short stature, occupation, poverty
Genetic factors
 Chorioamnionitis
Prior Preterm Birth
Incompetent Cervix
Mean cervical length
at 24 weeks: 35 mm
 Cervical Dilation 2~4
mm during 2nd
trimester: predict birth
prior to 35 weeks
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Infections
Bacterial vaginosis
 Tricomonas (low birth weight, preterm
birth, perinatal death)
 Periodontal disease
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Premature Membrane
Rupture
PPROM
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Incidence during 24~34 weeks
1.7 % of pregnancy
 20 % of all prenatal deaths
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
7 % delivery delayed > 48 hours
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Volume of amniotic fluid after PPROM
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Better outcome
Prognositc importance before 26 weeks
PPROM < 23 weeks:
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lung hypoplasia
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Antimicrobial therapy
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Prolong latency period after PPROM
If chorioamnionitis is diagnosed
Fever
 Vaginal delivery
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If PPROM beyond 34 weeks
Oxytocin to induction of labor
 C/S if indicated
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Preterm Labor
Preterm Labor
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Signs and symptoms
Painful or painless uterine contractions
 Pelvic pressure
 Menstrual-like cramps
 Watery vaginal discharge
 Low back pain
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Diagnostic critiria
Uterine contraction 4 in 20 mins
 8 in 60 mins with cervical change
 Cervical dilatation > 1 cm
 Cervical effacement > 80%
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Glucocorticoid
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Betamethasone
12mg IM stat and 24 hours later
 Effective: 24 hours after initial dose
 Effect up to 7 days
 Adverse effect:
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Pulmonary edema
 Infection
 Difficult glucose control in DM women
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Bed rest (+)
 Hydration (-)
 Antimicrobials (-, if no PPROM)
 Emergency cerclage (+)
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Drug to Inhibit Preterm Labor
Beta-Adrenergic Agonist
Ritodrine
 Beta-adrenergic receptor desensitization
 Side effect:
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Pulmonary edema
 Hyperglycemia
 Arrhythmia
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Magnesium Sulfate
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Calcium antagonist
Cleared almost by renal excretion
4 g loading dose 2 g/hr continuous dose
Therapeutic range:
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Deep tendon reflex disappear
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4~7 mEq/L
1 mEq/L = 1.2 mg/dl = 0.5 mmol/L
10 mEq/L
Respiratory arrest
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12 mEq/L
Prostaglandin Inhibitors
Indomethacin
 Total 24 hours dose < 200 mg
 Side effect:
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Oligohydramnios (reversible)
Calcium Channel Blockers
Nifedipine (adalat)
 Side effect:
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Hypotension
 Decrease uteroplacental perfusion
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Atosiban
Nonapeptide oxytocin analogue
 Competitive antagonist of oxytocininduced contractions
 Side effect:
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Nausea, vomiting, headache, dizziness,
money loss
 18000 NTD/day
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感恩