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Preterm Labor & Preterm Birth
Family Medicine Specialist CME
Vientiane, Lao PDR
December 10 – 12, 2008
Objectives
• Define preterm labor and recognize significance to infant mortality & morbidity
• Describe common causes of preterm labor
• Describe how to diagnose preterm labor
• Explain the management of preterm labor & preterm birth
Preterm Labor
• Regular uterine contractions
• Progressive cervical dilatation
• +/- effacement
• Less than 37 weeks gestation
• Usually results in preterm birth
Preterm Birth
• Birth occurring before 37 completed weeks of gestation
• Dated from Last menstrual period (LMP)
Incidence
• Occurs in 7 – 10% of all pregnancies
• Has not changed in 30 years in countries such like Canada
• Approximately 1 – 2% of pregnancies deliver before 34 weeks gestation
Significance
• Babies born >34 weeks gestation in centres with NICU have survival rates equal to babies born at term
• Babies born <34 weeks gestation have long term adverse outcomes– Respiratory complications– Central nervous system complications– Neurodevelopmental delays– Blindness & deafness
• Babies born <30 weeks gestation have high mortality and morbidity
Etiology
• Preterm pre-labor rupture of membranes• Spontaneous preterm labor with intact
membranes• Other causes
– Placental abruption– Chorioamnionitis– Gestational hypertension– Abnormal fetal monitoring findings– Intrauterine growth restriction
Risk Factors
• Prior history of spontaneous preterm birth
• Preterm pre-labor rupture of membranes
• Antepartum hemorrhage
• Uterine distension– Twins (multigestational pregnancy)– Polyhydramnios
• Incompetent uterus/uterine abnormality
• Fetal anomly
Risk Factors
• Infection– Chorioamnionitis– Bacteriuria– STI’s– Peridontal disease– Bacterial vaginosis + prior preterm birth
• Drugs, smoking (>10 cigs/day), lifestyle• Domestic violence• Demographic factors
– Maternal age <18 or >35 years of life– Maternal weight <55 kg - malnourishment
Diagnosis
• Early– Educate patients about early signs &
symptoms of preterm labor• Contractions• Vaginal fluid loss• Vaginal bleeding• Maternal perception of vaginal pressure, low dull
backache, vaginal discharge
Diagnosis
• Establish dates of pregnancy– LMP (Last Menstrual Period)– EDD (Estimated Date of Delivery)– Current gestational age
• Identify risk factors
• Evaluate for uterine contractions
• Assess for cervical changes
Management Objectives
• Early diagnosis of preterm labor
• Identify & treat underlying causes of preterm labor
• Attempt to arrest labor, if appropriate
• Intervene to reduce neonatal morbidity & mortality
Prolongation of Pregnancy
• Use of tocolysis to prolong pregnancy for 48 hours allows:– Betamethasone treatment– Transfer of mother to appropriate neonatal
centre for delivery of baby
Prolongation of Pregnancy
• Contraindications for continuing pregnancy– Gestational hypertension with proteinuria /
adverse events for mother– Chorioamnionitis– Mature fetus– Imminent delivery– Intrauterine death or lethal fetal anomaly
Betamethasone treatment
• Dose: 12 mg IM for 2 doses, 24 hours apart
• Requires 48 hours for maximum benefit
• Gestational age: 24 to 34 weeks
• Crosses placenta and accelerates lung maturity
• Helps prevent intra-ventricular hemorrhage and necrotizing enterocolitis
Antenatal Steroid Cautions
• If immediate delivery indicated, do not delay for steroid effect
• If cardiac disease, active TB, chorioamnionitis, placental abruption
• Transient increase in WBC count
Tocolytics
• Some evidence for:– Nifedipine (Calcium Channel blocker)– Indomethacin (Prostaglandin Synthetase
Inhibitor)• Gestational age <32 weeks
– Risk of fetal premature closure of ductus arteriosis
• 100 mg suppository PR for transport
Maternal Transport
• Mother should be transported to hospital best suited for delivery of neonate
• Requires transportation with skilled birth attendant
• Consider risk of delivery en route• Consider risk of journey to maternal /
neonatal well-being
Maternal Transportation
• Contraindications– Unstable mother– Abnormal fetal monitoring– Imminent delivery– Lack of skilled birth attendant to accompany
mother– Weather or hazardous conditions for travel
Prevention
• Screen & treat for asymptomatic bacteriuria
• Screen & treat for STI’s
• Education of patients for signs & symptoms of Preterm labor
Conclusion
• Diagnosis preterm labor early to provide for appropriate intervention and treatment
• Treat with betamethasone if appropriate to enhance fetal lung maturity
• Use tocolysis to allow for betamethasone to work and allow for maternal transfer to appropriate hospital